The asynchronous laser transponder can greatly enhance the functional distance of the satellite laser ranging. The formulae are deduced for the delay between the laser departure from the two terminals (the clock offset), the range between the dual stations, and the measuring time for the range. The formula of the clock offset is different from the classical formula and the practical formula applied in radio ranging. In order to get the correct formula of the clock offset, achieve the ranging error and verify the engineering feasibility, we designed and carried out the verifying experiment for asynchronous laser transponder. This experiment is also the first application of the new method of asynchronous laser transponder in our country. The experimental result shows that the asynchronous laser transponder system is feasible, which proves that our formula for the clock offset is correct. The accuracy of the new method locates the accuracy of reflex ranging of both terminals.