This paper is studying the fluid mechanics and heat transfer along the surface of are-type slotted fin in the finned heat exchanger by using the simulation software comsol multiphysics. The major study is the effect of the structure of fin to the fluid mechanics and heat transfer process, including the fin pitch, height of arc-type slit, the size of arc-type slit, the position of arc-type slit. And drawing the following conclusion: under the condition of low velocity, the fin pitch should be around 2.0 mm in considering the overall heat-transfer performance, and under the condition of large velocity, around 1.5 mm is better; When designing the arc-type slotted fin, the more larger the height of arc-type slit do, the better the overall heat-transfer performance; it is better if the start angle, as same as the position of arc-type slit, is less than 30°; the angle of arc-type silt ,as same as the size of arc-type slit, should be larger under the condition of meeting the demand of pressure drop.