Objective To analyze the clinical protection of petrosal vein during the microvascular decompression of primary trigeminal neuralgia. Methods 60 patients with primary trigeminal neuralgia treated from April 2016 to April 2017 in our hospital were selected. All the patients received the microvascular decompression. The subjects were randomly divided into study group and control group, 30 cases each group. During surgery, the control group received the electrocoagulation to cut off the petrosal vein with the affiliated branches; the observation group took the protection strategies on the petrosal vein and the affiliated branches. The adverse event rate for two groups was compared. Results After surgery, both of the groups were quite satisfactory. The control group had 24 cases with mild adverse reactions (80.00%) and 2 cases with serious adverse reactions (6.67%), the observation group had 16 cases with mild adverse reactions (53.33%) and 0 case with serious adverse reactions (0%) (P<0.05). Conclusion During the microvascular decompression of primary trigeminal neuralgia, the protection strategy of petrosal vein can greatly reduce the adverse event rate and avoid the serious adverse reactions