In order to study and summarize movement,tectonic deformation and strain accumulation evolution characteristics of the Longmenshan fault and its surrounding area reflected by GPS and cross-fault data before the MS8.0 Wenchuan earthquake,and study the possible physical mechanism late in the seismic cycle of the Wenchuan earthquake,we use GPS velocity during 1999~2007,GPS baseline time series on large scale during 1999~2008 and cross-fault leveling data during 1985~2008 to make analysis and discussion. (1)GPS velocity profiles show that obvious continuous deformation across the eastern Tibet before the earthquake distributed across a zone at least 500km wide,while there is little deformation in the Sichuan Basin and Longmenshan fault zone,which means that the eastern Tibet provides energy accumulation for the locked Longmenshan fault zone continuously.(2)GPS strain rates show that the east-west compression deformation is large northwest of the mid-northern segment of the Longmenshan fault zone,and deformation amplitude decreases gradually from far field to near fault zones,and there is little deformation in fault zones. The east-west compression deformation is significant surrounding the southwestern segment of the Longmenshan fault zone,and strain accumulation rate is larger than that of the mid-northern segment. (3)Fault locking indicates nearly whole Longmenshan fault is locked before the earthquake except that the hypocenter of the earthquake is weaker locked,and a 20km width patch in the southwestern segment between 12km to 22.5km depth is in creeping state. (4)GPS baseline time series in the northeast direction on large scale become compressive generally from 2005 in the north-south seismic zone,which reflects that relative compression deformation enhances. (5)The cross-fault leveling data show that annual vertical change rate and deformation trend accumulation rate in the Longmenshan fault zone are little,which indicates that vertical activity near the fault is very weak and the fault is tightly locked. By analyzing GPS and cross-fault data before the Wenchuan earthquake,we consider that the Longmenshan fault is tightly locked from the surface to the deep,and the horizontal and vertical deformation are weak surrounding the fault in relative small scale crustal deformation. The process of weaken deformation may be slow,and when close to large earthquake,the weaken deformation area may be larger. Continuous and slow compression deformation across the eastern Tibet before the earthquake provides dynamic support for strain accumulation in the Longmenshan fault zone in relative large scale crustal deformation.