The dimple and bump microstructures on 304L stainless steel surface are processed by modulating the power and pulse duration of a long pulsed laser, and their morphology features are observed. The research results show that dimples with good morphology can be obtained under short pulse duration and high power and the dimple depth and diameter increase first and then decrease with the increase of laser power when the pulse duration is fixed. In contrast, bumps with good morphology can be obtained under long pulse duration and low power, the influence of power on bumps is stronger than that of pulse duration, and when the power reaches a certain value, the bump height and diameter approach to saturation.