To obtain the analytical solution of cylindrical cavity unloading-contraction problem considering the effect of different degrees of intermediate principal stress, quantitative prediction of contraction and plastic deformation was conducted under a certain degree of unloading during cavity excavation. Based on the unified strength theory and by introducing the unloading factor and contraction coefficient, the dimensionless similarity solution of cylindrical cavity unloading-contraction was derived. Compared with the large strain solution without considering the influence of the intermediate principal stress, the effects of the influence coefficient of intermediate principal stress on the displacement and stress distribution of the borehole, and the effects of soil stiffness, cohesion, and friction angle on unloading-contraction were given. Results show that the larger the intermediate principal stress influence parameter b was, the smaller the borehole unloading-contraction effect was, and the essence was that the increase of b reduced the initial yield unloading pressure, delayed the appearance of the peripheral peak hoop stress, and helped to reduce the borehole wall plastic zone. The influence of b on the radial displacement and hoop stress of the borehole was not negligible, while the radial stress was less affected. Soil stiffness had a great influence on the relation between cavity unloading and contraction that the greater the stiffness was, the smaller the effect of b was. Based on the dimensionless unloading contraction solution of borehole, a more reasonable quantitative prediction of the radius variation of cavity at a specified unloading degree can be performed, which can be used in the practice of tunneling excavation and support, pile bearing capacity analysis after boring unloading, and stability analysis of well drilling.