Objective This study applied the Chinese Dietary Balance Index for Lactation (DBI-L) to assess the dietary quality and distribution characteristics of lactating mothers at different stages of lactation in five cities. Methods A total of 1531 healthy lactating mothers during puerperium were recruited from five cities, namely Tianjin, Lanzhou, Chengdu, Guangzhou, and Changchun. Basic information and dietary status were collected using a self-administered questionnaire and 1d 24h dietary recall method, and scores for each food group were calculated and evaluated using DBI-L. Results The dietary intakes of puerperal lactating mothers were characterized as excessive and insufficient, and the problem of insufficient intake was more significant, and most of the lactating mothers had dietary imbalances. Insufficient and excessive intakes of cereals, livestock and poultry meat, and chicken egg existed simultaneously, while the intakes of fruits, vegetables, milk, soy, nuts, fish, and shrimp were significantly insufficient. Nearly half of the lactating mothers had excessive salt intake. The difference in dietary quality among lactating mothers in different lactation periods was significant (P<0.01), and the problem of excessive dietary intake was more obvious in mature lactation, while the problem of insufficient dietary intake was more prominent in colostrum lactation. The problem of dietary imbalance was more obvious. The dietary quality of lactating mothers in different cities differed significantly (P<0.01), with cereal intake in Lanzhou significantly higher than in other cities and vegetables, egg, soybean and nut intakes generally lower than in other cities. The intakes of vegetables, fish and shrimp, livestock and poultry meat in Guangzhou were significantly higher than in other cities. The problem of over-intake and under-intake existed simultaneously in Lanzhou, where dietary under-intake was more prominent and the imbalance problem was more pronounced compared to the other four cities. Conclusion There was an imbalance in the dietary intakes of puerperal lactating mothers in China, as manifested by both excessive and insufficient intakes. Nutritional education and dietary intervention should be strengthened for puerperal lactating mothers, especially during the first lactation and in economically less developed areas.