Coupled heat transfer theory and EFD software are used to simulate the temperature field, flow field and pressure field of LED luminaire. According to the simulation result, the edge curve of heat flow field is extracted by image processing. After that, a model of new heat sink with curve shaped fins and the same weight is build based on the equation of the edge curve. This kind of structure could achieve uniform distribution of heat flow field, and make full use of ambient air to take away the heat faster. Simulation results show that, when ambient temperature is 20 ℃, the structure with curve shaped fins reduces highest temperature by 12 ℃, and highest relative pressure by 0.95 Pa. At the same time, flow velocity become more well-distributed, with much more fluid at higher flow rate. To further simplify the model, the curve shaped fins are optimized to inclined fins gradually tilting from the center to the sides. After the optimization, highest temperature drop by 7.1 ℃, compared with the former one. At last, contrast experiment is done to prove that the heat sink with inclined fins presents better cooling efficiency, and at the same time, has lower requirement for production and processing technology.