Objective This study summarizes the clinical data of all admitted children diagnosed with hypertension and to evaluate parameters which could differentiate secondary from primary hypertension in children. Methods All admitted children with a diagnosis of hypertension in our hospital from 2003 through 2007 were reviewed. Hypertension duo to a known disease is defined as secondary hypertention. Results Totally 304 children were included. Of them, 146 (48%) children had primary hypertension, 158 (52%) had secondary hypertension. By Chi-square tests, the rates were different significantly between the two groups in hypertension duration, gender, age, family history of hypertension, vascular murmur, Cushing sign, left ventricular hypertrophy in ECG, changes in ocular fundus, body mass index (BMI), blood uric acid, urine protein, blood urea nitrogen (BUN), creatinine (Cr), erect position renin angiotensin level, C reactive protein(CRP), erythrocyte sedimentation rate (ESR) and stroke. Logistic regression showed that positive family history of hypertension (OR=8.897), age of above 10 years old (OR=10.176) and increased BMI (OR=19.256) were risk factors of primary hypertension. Erect position renin angiotensin higher than 6ng/ml.h(OR=0.0593)was risk factor of secondary hypertension. Conclusions Secondary hypertension is more common in childhood hypertension. Family history of hypertension, age of above 10 years, increased BMI were risk factors of primary hypertension. Erect position higher than 6ng/ml.h was risk factor of second hypertension.