The large deviation in the accumulated rainfall measurements during heavy rainfall is a common problem in the application of laseroptical disdrometers, which needs to be improved. We start from the source laser and analyze its characteristics in depth and adopt a number of measures such as laser grating design, optimization algorithm, and scale calibration, so as to improve the precision of precipitation particle size measurement and the accumulated rainfall measurement accuracy. After the observation in different places in China, the results show that the design of the scale measurement accuracy of the laseroptical disdrometer has reached the goal of average absolute deviation of rainfall measurement accuracy of about 6% and the maximum deviation of less than 10% during heavy rains. Besides, the equipment has passed the test of heavy rainfall of typhoon and obtains better observation and application effects.