Bonding technique of III-V group materials is important for fabrication of optoelectronic devices and realization of opto-electronic integrated circuit (OEIC). However, electrical characteristics of the bonded interface, which is very important for the device design, were seldom investigated yet. Based on the thermionic emission theory and assumption that interface states distribute continuously in the band gap, and combined with distribution function, calculation model of interface states for bonded structure is set up. This model is applied to analyze the electrical characteristics of bonded GaAs/InP wafers, which were subjected to different surface treatment and annealing temperatures. Interface state density was firstly calculated after the definition of initialized electronic barrier of GaAs. Results show that sample bonded at 550°C with hydrophobic surface treatment has the lowest initial barrier height and the smallest interface state density. As a result, it performs best in terms of I-V characteristics.