Based on the digital teleseismic P-wave seismograms recorded by 15 long-period seismograph stations of the global seismic network,source rupture process of the April 14,2010 Yushu MS=7.1 earthquake is studied by a inversion method,and compared with surface rupture zone which was investigated after the earthquake.The result shows that the earthquake is a unilateral rupture event on the whole.The source rupture initiated at the hypocenter（33.2°N,96.6°E,focal depth 10 km）,and propagated to the southeast at first.The rupture broken though the ground surface departed from 20 km of the epicenter,it extended 50 km along strike,the maximal slip is 2 m.These results are coincide with the investigated feature of the surface rupture zone.