In order to maintain a good state of the UHV DC voltage divider so as to find out the problem in time, it is necessary to carry out a preventive test on it every year. It not only prolongs the outage time and may cause equipment and personnel safety problems due to often disconnecting lead. Combined with the structure characteristics of DC voltage divider itself installed on polar line and neutral line, this paper presents a test method of measuring high-low voltage arm capacitance and partial pressure ratio without removing lead, and uses the method to the actual test of preventive test of substation. Test results are compared with the test data over the years, and the results show that the proposed method can guarantee the test validity and reduce the workload of field test. This work is supported by Science and Technology Project of State Grid Corportation of China “Research and Development of Direct Current Measuring Device Test Method for DC Engineering”.