Nanosecond pulsed laser is used to blacken the surface of copper, and the reflectance and roughness of the samples are measured by a spectrophotometer and an optical surface profiler. The micro-nanostructure is observed by a scanning electron microscope (SEM), and the effect of scanning distance on blackening under unidirectional filling scan is investigated. The results show that different micro-nanostructures are formed after different scanning distances (grating-like, approximately grating-like, and coral-like, and so on), and the decrease of scanning distance can enhance light absorption obviously. When the scanning distance is 10 μm, the absorption of blackened area is over 97% in the wavelength band ranged from 200 nm to 760 nm, over 90% ranged from 760 nm to 1110 nm, and over 85% ranged from 1110 nm to 2500 nm. In addition, the effect of different filling directions at the second time under different scanning distances is also investigated. A certain enhanced absorption value is found after the second blackening compared to the first time, and the difference in absorption among different filling directions is diminished with the decrease in scanning distance.