In wireless sensor and actuator network(WSAN), in order to determine the location of sensors based on the range-based location techniques, estimating accurately the distances between sensors and actuators is very important. In this paper, based on the analysis of Generalized Chinese Remainder Theorem(CRT), some improvement to the Generalized CRT was made and an improved distance estimation algorithm which can be used in WSAN was proposed. In addition, the derivation and proof of the improved algorithm were provided. The simulation results have shown the validity of this algorithm.