It is easy to produce molten slag by using traditional laser cutting technology in laser cutting some special steel such as stainless steel and so on. The main reason is that oxidizing reaction will take place inevitably by using oxygen as aided gas. So high pressure and high purity N2 or inert gases are used as aided cutting gas in laser cutting stainless steel. After study of the forming principle and the rule of molten slag, a fine new laser cutting technology by using cyclone slag separator that will form rotating gas flow to control the direction of the flowing slag gas and oxygen as aided gas is presented. The experiments prove that by controlling the technical parameter reasonably, this laser cutting technology is practical and feasible. When the coaxial aided cutting gas is oxygen and the gas pressure is 300 kPa, the cyclone slag separator gas pressure is 100 kPa, the laser is TEM01and the output power is 500 W, the focal position is on the workpiece, and the cutting speed is 3 m/min, lubricous and dross-free cutting kerfs are obtained.