The invention discloses a fiber grating type pressure transducer for rock-soil complete stress measurement, comprising a spherical housing; each of the upper part and the lower part of the spherical housing is provided with three cylindrical holes; the cylindrical holes comprise a first diameter installation hole, a second diameter installation hole and a third diameter installation hole which are successively decreased from the surface of the spherical housing to the center of sphere; the first diameter installation hole is internally provided with a bearing plate, a stress transfer column and an induction film; the second diameter hole is internally provided with a vertical column and a fiber grating strainometer; and the third diameter installation hole is provided with an optical fiber. The fiber grating type pressure transducer can obtain the stress state of one point through a solving equation according to the measurement pressure of six pressure sensors. The fiber grating type pressure transducer is safe in usage, not interfered by the electromagnetism, can realize signal long distance transmission, and has characteristics of long term stability, large measurement range, high accuracy, pressure resistance, erosion resistance, etc.