Abstract: The irradiating style of laser relative to the flying cylinder has to be considered whether the laser is from land or air. With specific assumptions, the analytical expressions of heating power area density distribution on the side of the cylinder is deduced. According to an ideal scenario, analytical deduction is carried out on the incidence angle factor, the excursion of the light spot center and the deformation of the light spot shape. The analysis shows that even if the cylinder does not spin, the light intensity center would wander on the side of the cylinder and the light intensity distribution would vary, especially that along the axial direction would vary greater. It requires detail study on the procedure combined with reality later.