Soil surface roughness has been widely used for characterizing soil surface prof ile. To rapidly measure soil surface roughness in situ, a laser scanner is devel oped based on triangulation principle. Compared with traditional instruments, th is device has higher measurement resolution (01mm), precision positioning ab ility (1mm), and efficiency. A PDA (personal digital assistant) is used as datalogger, which can meet the requirements of portability, large data mem ory, and realtime data processing in field.