In order to guide tip clearance dynamic measurement and active control, a model of the turbine rotor of an air engine was built, and the effects of cracks of different depths and locations in the blade or disk were investigated, considering the thermal stress and centrifugal force of the rotor. The results show that the variation range of tip clearance increases with crack depth: the range increased by 0.11, 0.38 and 0.9 mm compared to the normal condition when the distance of crack to blade tip was 0.005, 0.025 and 0.04 m, respectively, with the ratio of the crack’s depth to width maintained at 0.5. Meanwhile, when the crack occurred at the blade root, the tip clearance variation range significantly increased compared with the effect of uniform stress, and the tip locus was greatly dissymmetric during the period of engine acceleration and deceleration.