In order to measure the local density pf states (LDOS) on each depth profile of the GaAs/Si interface by Auger electron spectroscopy, the Auger line shapes are carefully processed and the Auger line shape analysis is performed with the help of factor analysis. A series of corrections to remove the distortions of the peak shape are carried out. There are two chemical states coexisting in the interface. Some of the Si atoms will bond with As and transfer 0.3 p electrons per Si atom to As, and the others will keep the chemical state of pure Si with Si-Si bond. The top of the valence band of Si has a slight shift due to the bonding between Si and As, and the amplitude of the LDOS has a significant decrease.