Abstract: This paper uses the characteristics of light spots to determine the uncertainty of laser in the spot，which introduces error entropy into the uncertainty of laser points. Uncertainty in points the laser point density function is determined based on the characteristic of lasers. Laser point information entropy is derived based on the information definition，taking advantage of the relationship between the information entropy and the error entropy to derive laser point error entropy. Error entropy is the linear relationship of spot size based on the error entropy expression. Point cloud error entropy andaverage error entropy of each point was acquired according to point cloud spot actual area. The influence of incident angle on the uncertainty of laser points was analyzed by the relationship of incident angle and error entropy，and the best incident angle of scan was determined. A feasibility of point cloud uncertainty by error entropy was verified according to the analysis of point clouds by setting different scan intervals.