In order to study the ground potential rise of substations and the electromagnetic disturbance on secondary equipment induced by the system grounding short circuit or lightning faults, it is necessary to measure the transient potential of the substation grounding grid and the harassment voltage of the secondary equipment cable port. Therefore, based on the measuring conditions and requirements in substations, a ground potential rise test system with high voltage division ration and a wide frequency band is developed to apply to the complex electromagnetic environment of them. The hardware of the test system includes electromagnetic shielding box, independent power module, signal acquisition system and optical fiber communication module. Software is developed for the data communication between the test system and the upper computer based on Labview, to realize the disturbance voltage automatic measurement and storage. The professional performance test shows that the test system is suitable for the substation site test requirements in electromagnetic compatibility and measurement functions, and is capable to obtain the ground potential rise and harassment voltage waveform of the cable port in a 220kV substation field test excited by a surge voltage, proving the effectiveness of the test system.