This paper conducts an in-depth analysis of the theory and methods for differentiating and treating insomnia in Bu Ju Ji by Wu Cheng, a physician of the Qing Dynasty. By systematically sorting out the origin of Wu Cheng’s academic thoughts, this study explores his unique perspective on differentiating and treating insomnia, analyzes the compatibility rules of his core formulas and herbs, and reveals the characteristics of his medication use as well as its guiding value for later clinical practice. Research shows that Wu Cheng integrated the principles of the I Ching (Book of Changes) with medical theories to construct a theoretical system for consumptive diseases. In the differentiation and treatment of insomnia, he emphasized the dynamic balance of zang-fu organs, Qi, blood, Yin and Yang, with special attention to the impact of spleen-Yin deficiency on insomnia. He thus formed distinctive academic features, including treating both deficiency and excess, taking into account both Qi and blood, and regulating the spleen to protect the body’s defense system. In terms of medication, he was skilled in using herbs that are sweet and warm in nature for tonification, harmonizing Qi and blood, and invigorating the spleen to nourish Yin. These insights hold significant reference value for modern TCM (Traditional Chinese Medicine) in the treatment of insomnia.