The diurnal cycle of summer precipitation in Liaoning Province is investigated by using hourly raingauge data from 25 stations during 1961-2008. The results show there are strong regional characteristics of diurnal cycle and differences between coastal station and inland station. In general, the maximum precipitation amount of coastal station occurs at 04-08 BT before noon, while inland station’s diurnal cycle has a form of double peak, one before noon and one afternoon, and the maximum value occurs at 14-20 BT afternoon. The maximum precipitation frequency of coastal station is before noon, while the diurnal cycle of inland station’s frequency also has a form of double peak. The maximum value of precipitation with persistent 6 h or more occurs before noon, which is the reason for coastal station’s peak before noon. On the other hand, the inland station’s afternoon peak is attributed to the short time precipitation which is less than 6 hours and mainly caused by strong convection in the afternoon. The results also show that the diurnal cycle of precipitation can affect TS scores.