Abstract: Serica orientalis Motschulsky is one of the important pests in agriculture and forestry. From May to October 2020, this experiment collected and counted the number of adults of Serica orientalis Motschulsky adults in Dingxi City by using the insect situation prediction lamp and analysis population dynamic,the results showed that the pests occured in June 20, June 27, July 2, which occurred three harm peak of Serica orientalis Motschulsky adults. This time was that the best period for the prevention and control.