Abstract: The design principle and experiment result of novel a kind of strip integral mirror for high power laser processing are introduced. According to the geometrical optics, traditional surface of revolution of focal mirror is replaced by multistrip curved surface to form strip integral mirror. The experiment results show that after focusing, the laser beam present the rectangular slit of light with uniform distribution of light intensity, which can improve the processing quality for laser heat treatment, laser hardening, laser cladding and laser welding with powder.