Objective:To investigate the pathogenesis of Yang and insomnia. Methods: This paper analyzes the Yangqi influence the physiological mechanisms of sleep.The sleep is impacted from lack of heart Yang,spleen Yang,kidney Yang and systemic Yang .We explore the mechanism of Yangxu insomnia, and give an treatment example. Conclusion: When we treat patients with insomnia, we should analysis of the patient's symptoms in detail,and follow the principles of diagnosis and treatment to choose a best way to cure the insomnia.While encountering a Yangxu insomnia patients in clinical practice,we should decisively apply yang drug to the patient. We can't stick to conventional thinking,however,the little possibility may bring surprise to treatment of insomnia,and we must try our best to relieve the suffering of insomnia patients.