Transponder overcomes the large R4 signal loss characteristic of traditional satellite laser ranging,thus it can range to interplanetary distance.Though studying balanced system and sampling rate,one can place as much of the transponder link burden on the Earth station as necessary (within reasonable engineering or economic limits) in order to achieve a ‘balanced’ and optimized link.Based on the balanced system,we can perform asynchronous transponder simulation experiment.Evaluation the ranging capacity of SHAO′s SLR system is carried out.Finally，we introduce MLA system in interplanetary ranging.