Objective To investigate the dietary changes of convalescents over the past 30 years, so as to provide a basis for developing a scientific dietary supply model. Methods The convalescents in Hangzhou sanatorium and Qingdao sanatorium were sampled randomly, and a 3-day dietary survey was conducted respectively in 1992, 2002, 2010 and 2022 using the weighing method. The dietary quality was evaluated using the recommendations issued by the Chinese Nutrition Society. Results During the past 30 years, the intakes of grain and salt decreased year by year, but the intake of salt was still more than twice as much as the recommended intake (P<0.05). The intakes of vegetables, fruits, meat, aquatic products, milk and vegetable oil increased year by year, but the intake of milk was still lower than the recommended intakes (P<0.05). The intake of vegetable oil was nearly double of the recommended intakes (P<0.05). Except for carbohydrates, the intakes of other nutrients showed an increasing trend, in which energy, protein, fat, niacin, vitamin E, iron and zinc intakes were significantly higher than the recommended intakes, and the differences were statistically significant (P<0.05). Conclusion The dietary structure and nutrient intakes of convalescents have been significantly improved over the past 30 years. However, carbohydrate intake was still insufficient, while energy, fat, protein, niacin, vitamin E, irons, and zinc intakes were excess. It is suggested that sanatorium units should strengthen nutrition education, implement precision nutrition guarantee mode, increase nutrition and health care efficiency, and improve the nutrition and health status of convalescents.