The structure changes of a Cu Σ=5（310）/［001］ symmetrical tilt grain boundary are investigated using the molecular dynamics method by heating and quenching. The simulated results showed that with increasing temperature,there are structure changes of the grain boundary. At a temperature significantly below the bulk melting point of copper,the grain boundary undergoes a structure change,and there exists the crystal-melt coexistence in the grain boundary zone. The grain boundary structures can be changed by quenching,which are compared to those at the same temperatures by heating.