Abstract The CrSiN films with different Si contents were deposited on stainless steel and silicon substrate (100) by reactive magnetron sputtering. The microstructures, mechanical properties and tribological properties were investigated as a function of Si/(Cr+Si) ratio. It was found that the hardness reached its maximum value of approximately 22GPa. The wear mechanism of CrSiN films were investigated as the Si/(Cr+Si) ratio changed in the air and water environment. The tribochemical reaction was found to occur in the wear contact area, and this caused CrSiN films to form the amorphous oxide layer which was the reason for the low fiction coefficient and low wear rate.