In this paper, the 2015 Nepal Earthquake sequence, both the main shock (M_W 7.8) on 25 April 2015 and the major aftershock (M_W 7.2) on 12 May 2015 are investigated by using co-seismic DInSAR and GPS measurements. Source model and slip distribution of both events are determined using geodetic inversion based on an elastic dislocation model. The optimised source model for the main shock shows a thrust fault striking 285.9° NW-SE and dipping 7.7° NE with a slight right-lateral component. The maximum slip of this event is up to 5.1m. The peak slip of distributed slip model for the major aftershock was found at the similar depth of main shock. The triggering relationship between main shock and major aftershocks is demonstrated based on the calculation of Coulomb stress change.