[Abstract] Objective To explore the protection of the facial nerve during operation for CPA tumor and evaluation of its function after operation. Methods 32 patients with CPA tumor were operated under the Facial muscle EMG monitoring and the operating microscope.And stimulate the facial nerve near the brainstem to evaluate the prognosis at the end of operation. Results Total removal was achieved in 30 patients(93.75%).The facial nerve was preserved anatomically in 29 patients(90.63%).The function of facial nerve was kept well in 26 cases(81.25%).The stimulative intensity value is related to the postoperative function of facial nerve. The stimulative intensity is the lower, the function of facial nerve is the better.when stimulative intensity is 0.05～1.5mA, The function of facial nerve may be 88.46% inⅠ、Ⅱgrade afters 12 months. Conclusions Intraoperative facial nerve monitoring can increase the anatomical and function preservation rate of facial nerve and also can evaluate its function after operation.