The predatory functional response, predatory preference and auto-interference response of Phytoseiulus persimilis to different stages of Tetrarcychus urticae were examined under laboratory conditions, to determine the control potential of the predatory mite P. persimilis against T. urticae. The results showed that the functional response of the P. persimilis to T. urticae fitted well with the Holling II model. The predatory capacity of P. persimilis decreased with spider mite size. Predation was greatest on eggs, followed by nymphs and adults. The maximum predation capacity of female adult P. persimilis on the three stage of T. urticae were 333.33, 45.45 and 12.99, respectively. When the different stages of T.urticae coexist, P. persimilis preferred T. urticae nymphs to eggs and adults. At the same prey density, the predation rate of P. persimilis on the adults of T. urticae decreased with the increase of its own density, which indicated that the intraspecific interference effect existed in P. persimilis.