In this study, a soil pressure sensor based on additive manufacturing (AM) technology and fiber Bragg grating (FBG) is designed. The calibration experiment results indicate that the sensitivity, minimum resolution, and measurement range of FBG soil pressure sensor are 0.2 pm/kPa, 5 kPa, and 1000 kPa, respectively, and that the sensitivity of the sensor can be adjusted as per requirement using AM parameters (filling density, filling material) to reduce measurement errors. The experimental results of the indoor model box show that, the sensor can effectively measure the internal pressure of soil during test loading and that measurement range is wide. The resolution and range can be customized according to real-world conditions, which provide a new approach for internal pressure monitoring of the soil.