Objective To investigate the relationship between the changes of blood lipid and age, coronary artery disease and its severity in children with Kawasaki disease (KD). Methods A total of 241 children with acute KD admitted from January 2018 to December 2020 were selected as the study subjects (KD group), and 30 healthy children who underwent physical examination in our hospital were selected as the control group. The levels of serum total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL-C) and high density lipoprotein (HDL-C) were compared between the two groups. The differences in blood lipid levels among KD children of different ages, with or without coronary artery lesions (CAL) and with different severity of CAL were compared. Results There were 241 patients (135 boys and 106 girls) in KD group, and the median age was 2.17 (1.04-4.00) years. Forty children were <1 year old, 120 were 1-3 years old, and 81 were >3 years old. There were 94 children in the CAL group and 147 in the non-CAL group. In the CAL group, 68 children were grade Ⅱ, 17 were grade Ⅲ and 9 were grade Ⅳ. The control group included 30 patients (14 boys and 16 girls) and the median age was 3.00 (2.00-5.00) years. The TG and LDL-C levels of KD children in the acute stage were significantly higher than those in the control group, while the levels of TC and HDL-C were significantly lower than those in the control group, and there were statistically significant differences (P<0.05). There were statistically significant differences in TG among different age groups (P<0.05), and TG showed a decreasing trend with the increase of age. TG in the CAL group was significantly higher than that in the non-CAL group, and the difference was statistically significant (P<0.05). There were statistically significant differences in TG among CAL groups with different severity (P<0.05). Conclusions In the acute stage of KD, the levels of TC and HDL-C were decreased, while the levels of TG and LDL-C were increased. The TG level was correlated with the age, whether CAL was complicated or not, and the severity of CAL in KD children.