The invention discloses a pressure chamber for a pile and soil contact surface shearing characteristic testing device. The pressure chamber comprises a top plate, a bottom plate and a plurality of outer side vertical plates which are arranged between the top plate and the bottom plate in a sliding manner, wherein a mold cavity for placing a pile test sample and a soil test sample is commonly enclosed by the top plate, the bottom plate and the plurality of outer side vertical plates; the mold cavity of the pressure chamber is internally provided with a retractable chamber; the retractable chamber is enclosed by the top plate, the bottom plate and all the outer side vertical plates; two retractable plates, which are vertical to each outer side vertical plate, are arranged at the inner side of each outer side vertical plate in the vertical direction; upper and lower ends of the retractable plates are in sliding connection with the top plate and the bottom plate respectively; in a testingprocess, horizontal push forces are applied to different sides of the pressure chamber through a plurality of push force devices of the testing device, and a horizontal force is applied to each side of the pile test sample through squeezing the soil test sample; horizontal pressure with the same size or different sizes is applied to different directions of a pile periphery and an actual working condition is effectively simulated. The pressure chamber can be used for testing pile foundations with regular section shapes, such as round piles and square piles.