[Objective] To investigate the treatment effect of primary trigeminal neuralgia by using xiao-chai-hu decoction combined with Carbamazepine. [Methods] 70 patients with primary trigeminal neuralgia treated in the department of internal medicine of our hospital from June 2011 to June 2012, and randomly divided into experimental group and control group, each group of 35 cases. Patients in the control group taking Carbamazepine; Patients in the experimental group taking Carbamazepine combined with xiao-chai-hu decoction.To observe the clinical efficacy and side effects in two groups after 1 month of treatment, doing statistical analysis. [Results] The experimental group and control group total effective rates were 85.71%, 62.86% repectively, there was statistical y significant difference; the patients in the experimental group after treatment, pain degree and adverse reaction rate were significantly lower than the control group, there were significant differences. [Conclusion] Carbamazepine combined with xiao-chai-hu decoction has good curative effect for primary trigeminal neuralgia, worthy of clinical application.