A three-dimensional local-scale P-velocity model down to 25 km depth around the main shock epicenter region was constructed using 83821 event-to-receiver seismic rays from 5856 aftershocks recorded by a newly deployed temporary seismic network.Checkerboard tests show that our tomographic model has lateral and vertical resolution of～2 km.The high-resolution P-velocity model revealed interesting structures in the seismogenic layer:(1) The Guanxian-Anxian fault, Yingxiu-Beichuan fault and Wenchuan-Maoxian fault of the Longmen Shan fault zone are well delineated by sharp upper crustal velocity changes;(2) The Pengguan massif has generally higher velocity than its surrounding areas,and may extend down to at least～10 km from the surface;(3) A sharp lateral velocity variation beneath the Wenchuan-Maoxian fault may indicate that the Pengguan massif’s western boundary and/or the Wenchuan-Maoxian fault is vertical,and the hypocenter of the Wenchuan earthquake possibly located at the conjunction point of the NW dipping Yingxiu-Beichuan and Guanxian-Anxian faults,and vertical Wenchuan-Maoxian fault;(4) Vicinity along the Yingxiu-Beichuan fault is characterized by very low velocity and low seismicity at shallow depths,possibly due to high content of porosity and fractures;(5) Two blocks of low-velocity anomaly are respectively imaged in the hanging wall and foot wall of the Guanxian-Anxian fault with a～7 km offset with～5 km vertical component.