Objective To analyze the clinical data of children with primary hypertension and secondary hypertension in order to provide reference for accurate diagnosis and for early detection of target organ damage in case of primary hypertension.Methods All the children who were diagnosed with hypertension and hospitalized between January 1992 and May 2016 were enrolled in this study. Hypertension was classified as primary and secondary based on the etiology of hypertension. Data was analyzed with SPSS 17.0 software.Results (1)The average age of primary hypertension patients was 11.76 years old, and the mean BMI was 26.90 kg/m², which were higher than those of secondary hypertension patients with statistically significant difference (P=0.000). (2)The composition ratio of secondary hypertension during infancy, preschool period, school age and adolescence was 94.7%、48.3%、17.0% and 8.6% respectively. Adolescents were more vulnerable to primary hypertension than children of other ages. (3) 59.42% of secondary hypertension patients had kidney disease. Blood pressure was higher in secondary hypertension patients.(4) Target organ damage was present during diagnosis in most of the patients with primary hypertension. Elevated levels of serum or urine β₂-microglobulin could be an earlier indicator of kidney damage. In the target organ damage group, the mean diastolic blood pressure and insulin level were higher.Conclusions Patients with secondary hypertension were younger than patients with primary hypertension, and blood pressure was higher. The causes of secondary hypertension are mainly kidney and vascular lesions. Target organ damage can be detected during diagnosis in most of the patients with primary hypertension. The higher diastolic blood pressure and insulin levels, the more likely target organ damage can be.