The magnetic properties and fluidity of a magnetic fluid have great potential applications in the field of temperature and magnetic field sensing. The combination of a magnetic fluid and an optical fiber sensing structure can modulate the light wave according to the changes in external temperature and magnetic field and obtain the sensing variation of temperature and magnetic field by demodulating the parameters of the characteristic spectra. This review summarizes the research progress of temperature and magnetic field sensors based on magnetic fluids according to different combinations of magnetic fluids and sensing structures. Furthermore, it introduces the temperature and magnetic field sensors based on mode interference, evanescent wave, fiber grating, fiber ring mirror, photonic crystal fiber, surface plasma, and Fabry-Perot interference. This review analyzes the sensing principle and sensitivity of each sensing structure and presents the future development trend. The temperature and magnetic field sensor with special fiber filled by magnetic fluid is shown to have a high sensitivity, a stable structure, and a strong anti-interference ability.