The invention belongs to the field of a soil internal pressure measuring method, and discloses a soil pressure measuring method with a variable measuring range based on a Bragg fiber grating. The method includes following steps: (1) selecting materials and dimensions of a cantilever beam and a film according to the dimension of a measured object and a measuring requirement; (2) installing a Braggfiber grating sensor on the cantilever beam to enable the Bragg fiber grating sensor and the cantilever beam to be tightly combined, connecting a free end of the cantilever beam and the film togetherthrough a rigid dowel bar, and connecting the Bragg fiber grating sensor to an optical fiber signal analysis processing device through an optical fiber; (3) fixing a fixed end of the cantilever beam to a sensor cavity, and placing a whole soil pressure transducer in the measured object; and (4) continuously measuring a strain value of the Bragg fiber grating sensor, and calculating a local pressure of the measured object. According to the method, the problem of precision measurement of soil pressure of different measuring ranges in the soil can be solved, the measuring requirement of the wide-span measuring range can be satisfied, the measuring precision of the sensor is high, and the security is high.