Ag6O2/SnO2 interface bonding of Ag/SnO2 composites was simulated by HRTEM image analysis and first-principles calculations. Results show that there is lattice match between the interfaces of SnO2(10) and Ag6O2(101). According to cohesive energy, population and density of state (DOS), it is found the bonding of the two free interfaces is in good agreement with the experiment results. Furthermore, the electron density difference verifies the undecomposed Ag6O2 provided an oxygen-rich environment for Sn, which is favorable for SnO2 particle formation. At last the relaxation state of surface atoms in the interface was analyzed