Abstract The reaction mechanism of producing hydrogen via water splitting on the different surfaces of cubic silicon carbide (3C-SiC), the adsorption energy and the activation energy have been studied here by using density functional theory. The results indicated that the adsorption behavior of water molecule could take place on 3C-SiC’s different surfaces and it leads to the surface reconstruction. Besides, the water splitting reaction is found to be a thermally activated process, and the first hydrogen atom is easier decomposing from the adsorbed water molecule than the second one for most of the 3C-SiC surfaces. Furthermore, the water molecule that splitting on 3C-SiC (111) surface requires relatively small activation energy by contrast with other surfaces. Photon excitation is considered to be essential for the overall water splitting reaction to proceed further.