Abstract:On the basis of the data of Fujian GPS stations, TAIW and TWTF key observation stations during 1995 to 2003, the variations and relative variations of the lengths between Fujian GPS stations and TAIW and TWTF stations are calculated, in the meantime,strain tensors of TAIW and TWTF stations are also calculated with genetic algorithm. The results show that the crustal relative movement of Taiwan strait is in the tensile state during both the periods of 1995 to 1997 and 2001 to 2003, but the magnitude and the direction of principal strain in the two periods are with a wide variation that may reflect the process of strain energy from accumulation to release before and after the M7.6 ChiChi earthquake in 1999.