The fabrication of polymethyl methacrylate (PMMA) gradient wetting surfaces using femtosecond lasers is significant for controlling droplets in microfluidic channels. In this paper, parallel microgroove structures are fabricated on PMMA surfaces using femtosecond laser. Gradient wetting surfaces with different properties are obtained by designing laser energy density parameters. Contact angle measurements, laser confocal microscopy, energy spectrum analysis, and scanning electron microscopy are used to measure the contact angle, roughness, chemical element composition, and surface morphology of PMMA surfaces, respectively. A high-speed camera is used to observe the spreading trend of droplets on gradient wetting surfaces. The results show that as the laser energy density increases, the surface contact angle first increases and then decreases. The surface roughness parameters, root-mean-square height and arithmetic mean height, both exhibit an upward trend. The content of carbon on the surface decreases while the content of oxygen increases. The larger the gradient difference of the gradient wetting surface, the faster the droplet spreading speed. This study on the reliable control of surface wettability by femtosecond laser provides a theoretical reference for the fabrication of PMMA microfluidic channels.