Abstract: Liu Baoyi was a famous febrile disease expert in the late Qing Dynasty, who innovated the theory of latent febrile disease. Liu proposed that the deficiency of kidney essence and the deficiency of healthy qi were the prerequisites for the latent cold evil, and the exogenous cold evil was the inducement of the disease. He advocated the treatment of latent febrile disease based on the six meridians, with the two ideas of eliminating evil qi and strengthening healthy qi as the outline, and the general principle of treatment was to relieve heat, nourish yin and expel evil qi. He attached importance to the coordination of medicine and food, made good use of fresh medicine, attached importance to drug processing, emphasized the use of herb processed by herb, and adapted the medicine according to the syndromes. He preferred to use co-processed products for clinical use. The study of Liu's academic thoughts and medication characteristics in treating latent febrile diseases is of great value in guiding the treatment and medication of various infectious and epidemic diseases with fever characteristics nowadays.