Abstract: This paper deals with the probability and practicality of the Laser Ranging to active fault.Applying the mathematical model based on the Kapoller parameters,an analog computation for district Songpan,in Szechuan Province has been carried out.Some problems are discussed in this paper,such as,orbital parameters have to be slacked off and two computational methods could be used for this purpose;it will not be convergent if only one circle data is used;the zeropoint error for a clock can't be solved and so forth.