Li Yu's Random Thoughts in Qing Dynasty is a classic of health preservation. * * * It consists of eight parts: Ququ Department, Sports Department, Volume Department, Living Room Department, Home Appliances Broadcasting Department, Drinking Restaurant Department, Planting Department and Nursing Home Department, and discusses opera, singing and dancing, costumes, ability training, gardens, architecture, flowers and nursing homes. Nursing department is an important document for health preservation. The book "Casual Love" is close to the vernacular at that time, easy to understand and humorous, which makes the boring health theory interesting. The theory of health preservation had a far-reaching impact at that time and later. 1935 Lin Yutang's English version of My Country and My People gave a high evaluation of the book, which was regarded as "a guide to China people's life art".