Abstract： Objective： To observe the clinical effect of modified Mengshi Guntan tang combined with zolpidem for insomnia of phlegm- heat harassing the interior type and its effects on cognitive function. Methods：A total of 102 cases of patients with insomnia of phlegm- heat harassing the interior type were divided into the control group and the observation group according to the random number table method， with 51 cases in each group. The control group was treated with zolpidem，and the observation group was treated with modified Mengshi Guntan tang combined with zolpidem. Both groups were treated for four weeks. Clinical effects and the incidence of adverse reactions were compared between the two groups. The polysomnography monitoring indexes and cognitive function were compared between the two groups before and after treatment. Results：The total effective rate was 92.16% in the observation group ，higher than that of 76.47% in the control group(P＜0.05). After treatment，sleep efficiency(SE) in the two groups were increased when compared with those before treatment，total sleep time(TST) was prolonged，sleep onset latency(SOL) was shortened，and awakening times(AT) was decreased，differences being significant (P＜0.05). SE in the observation group was higher than that in the control group，TST was longer，SOL was shorter， and AT was fewer， differences being significant(P＜0.05). After treatment， scores of Mini- Mental State Exam(MMSE) and Montreal Cognitive Assessment(MoCA) in the two groups were increased when compared with those before treatment(P＜0.05)，and the two scores in the observation group were higher than those in the control group(P＜0.05). The incidence of adverse reactions was 5.88% in the observation group， lower than that of 19.61% in the control group(P＜0.05). Conclusion： Modified Mengshi Guntan tang combined with zolpidem has a defined effect in the treatment of insomnia of phlegmheat harassing the interior type，which can effectively improve sleep quality and cognitive function，with high safety.