For the field of ocean depth detection, a small volume diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure is made. The length and diameter of the fiber Bragg grating pressure sensor are approximately 40 mm and 20 mm, respectively. The diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure uses an ultrashort fiber Bragg grating string. There are two fiber Bragg gratings on the ultrashort fiber Bragg grating string. The length of the two fiber Bragg gratings is 1 mm, and the interval between them is 20 mm. One fiber Bragg grating is used to measure pressure, and the other fiber Bragg grating is only affected by temperature, which can eliminate the influence of temperature on the pressure measuring fiber Bragg grating. The optical fiber is encapsulated in a metal tube a short distance away from the measuring pressure fiber Bragg grating. The end of the metal tube is fixed on the elastic metal diaphragm by a laser welding process. In this way, the optical fiber and metal diaphragm are not fixed by epoxy adhesive directly, which can avoid the influence of aging and creep of epoxy adhesive on the performance of the diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure. In the measuring range of 0.6 MPa, the theoretical pressure sensitivity of the diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure is -1.214 nm/MPa, and the pressure sensitivity of the diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure obtained by the finite element analysis method is -1.364 nm/MPa. After the diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure is fabricated, the pressure and temperature characteristics of the sensor are tested. With the help of a fiber Bragg grating only affected by temperature, the influence of temperature on the pressure measuring fiber Bragg grating is eliminated through calculation. The actual average pressure sensitivity of the diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure is -1.728 nm/MPa. Moreover, the linearity of the boost and buck curves of the diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure is more than 99.9%, and the boost and buck curves of the diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure also coincide well. In addition, the best way of the tail fiber seal, the reason of the different temperature response characteristics of the double fiber grating, the method of improving the linearity and coincidence degree of the pressure curve, the reason and solution of affecting the stability of the sensor, and the reason of improving the sensitivity of the measured pressure are discussed. First, when the thickness of the metal tube that encapsulates the optical fiber is relatively thin, comparative experiments show that the method of sealing the fiber tail with epoxy glue is better than laser welding. By sealing the fiber tail with epoxy glue, the wavelength shift of the fiber Bragg grating can reach 2 nm. It can be seen that sealing the tail of the optical fiber with epoxy glue more easily maintains the prestress applied to the optical fiber. Second, a temperature response test experiment of a diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure is carried out. The experimental results show that the temperature response of the fiber Bragg grating and pressure response of the fiber Bragg grating are slightly different. Combined with the simulation analysis, it is found that the main reason for the difference in the temperature response trend of dual fiber Bragg gratings is the defect of the structural design. Third, to improve the linearity and coincidence of the boost and buck curves of the sensor, temperature and pressure aging processes are added to the sensor manufacturing process. The experimental results show that these methods are effective. Next, considering the influence of an optical fiber tail wobble on the stability of a diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure, it is suggested to use apodisated linearly chirped fiber gratings or set up a region to isolate external forces to solve the problem. Finally, the problem that the actual pressure sensitivity of a diaphragm-type fiber Bragg grating pressure sensor with a temperature compensation structure is higher than the theoretical value is discussed from several angles. The main reasons are that the effective length of the fiber Bragg grating decreases due to the flow of epoxy glue and the pressure sensitivity of the fiber Bragg grating increases due to the increase in prestress.