Model forecast performance and forewarning service validity of disastrous heavy precipitation have been among the chief concerns in professional meteorological service. In view of these concerns, the evaluation of the power-grid-system-oriented meteorological forewarning for heavy precipitation in the main flood season (June-September, 2019) in the Beijing-Tianjin-Hebei Region is chosen as an example, in order to carry out in-depth analysis on using MODE (method for object-based diagnostic evaluation) in the inspection of short-term forecast and nowcast from two aspects, namely, target recognition of precipitation and target matching of precipitation. The results show that heavy precipitation in the main flood season of the Beijing-Tianjin-Hebei Region is mainly concentrated from afternoon to the first half of the night, characterized by large in precipitation intensity, small in range, easy false-alarms, and difficulty in predicting their spatial characteristics. The correlation coefficient of diurnal variation of the heavy precipitation frequency of short-term forecast and nowcast ranges from 0.78 to 0.94, while that of the diurnal variation of range is from 0.6 to 0.82. The forecast effect of moving path and rainfall intensity is slightly better than that of the falling area. The shorter the forecast time, the better the forecast effect of heavy precipitations and their spatial characteristics. The comprehensive forecast evaluation method put forward in the paper can make up for the shortcomings of traditional inspection methods. It can explore the potential and limitations of forecast, and provide reference for accurate and specialized meteorological services.