The optical disdrometer of Dongying Meteorological Bureau was put into use in 2012. In order to assess the accuracy of the detected precipitation, the precipitation data of 46 months by the automatic weather station (AWS) and by the optical disdrometer at Dongying National Meteorological Station from 2012 to 2017, a total of 245 precipitation processes and 1 302 hourly precipitation data, are collected. The observation data by these two instruments are compared and analyzed according to different precipitation grades. The results are as follows. 1) For light rain, the precipitation by the optical disdrometer is averagely 0.38 mm more than that by the AWS, and the greater the precipitation, the greater the difference； for moderate rain, the difference is relatively small, and the precipitation by the former is only 0.24 mm more; for heavy rain, the precipitation by the former is about 2.8 mm less; for rainstorm, the precipitation by the former is usually more. 2) When the hourly precipitation is less than 2.5 mm, the precipitation by the optical disdrometer is about 0.1 mm more than that by the AWS; when it is between 2.5 mm and 4.9 mm, inclusive, the average difference is 0.0 mm; when it is between 5.0 mm and 16.0 mm, inclusive, the precipitation by the optical disdrometer is obviously less than that by the AWS, which is about 0.9 mm; when it is between 16.0 mm (exclusive) and 20.0 mm (inclusive), the precipitation by these two is close; when it is more than 20.0 mm, the precipitation by the optical disdrometer can probably be extremely more or extremely less or close to that by the AWS. 3) As for snowfall, the precipitation by the optical disdrometer is usually significantly more. 4) The trend of accumulated precipitation by these two instruments is in conformity, and the minute precipitation by the optical disdrometer can reflect the precipitation peaks and changes of precipitation intensity. It can be seen from the analysis that the precipitation data by the optical disdrometer is reliable and can play a more important role in the observation and correction of precipitation phenomenon, the evaluation of weather modification effect, short-range forecasting, and nowcasting.