Behavior of the transversal crack and the longitudinal crack on slab surface during V-H rolling was simulated by the FEM. The contact pressure on crack surfaces and the crack-tip stress change rules during rolling were analyzed. Results show that the contact pressure on crack surfaces decreases and the tensile stress appears at crack tip in the zone of slippage on the delivery side, which may make the cracks propagation. For the phenomenon, the stress distribution along rolling direction and along width direction in rolling are analyzed, and the influence of forward slip on the closure and growth of the surface transversal crack and the surface longitudinal crack are discussed. Results support some significant information for researching the behavior of the slab surface defects in rolling process.