In the development process of a spaceborne laser range finder, how to test the performance indexes of the range finder on the ground is critical. According to the operation principle of a pulse laser range finder, a high precision dynamic testing system based on the photoelectric time delay method is designed. The system error which may affects system precision is analyzed. Finally, the measurement of the ranging accuracy of the laser range finder is realized. Compared with the traditional testing method, this method has the features of large dynamic range and high precision. The experimental results show that the testing system has its simulation range of 15 m to 30 km and its simulation accuracy better than 0.15 m. Because of easy operation and strong practicability, the system can meet the testing needs of all kinds of current laser range finders.