Abstract: Using the ECMWF fine gird,GRAPES＿GRAPES and 822 automatic stations data from June to August during 2016-2018 to study the forecast methods of short-time heavy rainfall（general short time heavy precipitation and extreme short-term heavy precipitation） in Heilongjiang Province from June to August and the fusion of various impact factor indicators and them.Use double-line interpolation or adjacent grid method,quantile method,batching method,elimination method,multiple analysis method,etc.to form an objective forecast method based on water vapor,instability,and uplift.The results show that the environmental background of heavy rainfall is not only limited by the thresholds of various physical factors,but also closely related to their fusion.There are a certain ten-day difference and daily difference among various factors.The thresholds related to water vapor are greater at night than that during the day,and thermal instability is higher during the day than that at night.The thresholds of the factors related to water vapor content in mid-to-early June are smaller than that in other time periods.Due to the suddenness of heavy precipitation,local topography and research methods,and the characteristics of the model itself,the forecasting rate of false alarms is very high,the rate of under-reporting is low,and the TS score is the lowest,and reduces with the decrease of the distribution density of heavy precipitation. In the general heavy precipitation test,the TS score of the point-to-point test of the two modes is about 0.015,and the TS scores of the point-to-surface test with radius of 14 km and 40 km are about 0.03 and 0.08.In the extreme heavy precipitation test,the TS score for the two models is about 0.004 for point-to-point tests,and the TS for points-to-point tests for 14 km and 40 km are about0.007 and 0.02.Due to the relatively large distribution density of heavy rainfall in July,the test results are relatively good.The general heavy rainfall test TS score of EC fine grid is higher than that of GRAPES＿GRAPES,while the extreme heavy rainfall test TS score is just the opposite.