With the acceleration development of cities construction and the expansion of cities. Cities’ power load is increasing. The original cities’ overhead transmission line and cable has can’t meet the needs of city electricity consumption, Because the cable can through the tunnels and underground installation, high voltage large cross-section transmission cable install more and more long, support clamp is applied more and more widely. In this paper, we study the loss of high voltage large cross-section transmission cable support clamp, in the case of current carrying capacity remains the same, set up the support clamp’s math model, through the simulation of SOLIDWORKS and COMSOL, finally, we get the different material’s loss.