A gradient wettable surface can make a droplet autonomously flow in a pre-determined direction. Therefore, this method is important for various applications. In this study, a method is developed to quickly fabricate a gradient wettable surface on the surface of 304 stainless steel using nanosecond laser ablation and heat treatment. The surface microstructure, chemical composition, and contact angle are observed and characterized via scanning electron microscopy, energy spectrum analyzer, and contact angle measuring instrument. A high-speed CCD camera is used to observe the flow of liquid on the gradient wettable surface. The experimental results show that the content of the carbon (C) on the surface is an important factor that affects surface hydrophobicity after laser processing. For 304 stainless steel, short-time heat treatment at temperature of 200 ℃ accelerates the increase of the C content, realizing fast curing of contact angle. The uniformly wettable surfaces with different contact angles can be obtained by designing the surface microstructure of the target. Then, the surfaces with different wettability gradients can be obtained by designing the surface microstructure distribution. The flow distance and velocity of the liquid droplet on the target surface can be controlled by changing the surface microstructure distribution.