By using of a nonrandomized experiment scheme and the data of rainfall and inflow of Gutian Reservoir between 1960 and 2007, the effectiveness evaluation method of precipitation enhancement effectiveness for water storage was studied based on the drainage area rainfall, inflow and runoff coefficients of the reservoir. After the reasonable precipitation enhancement operation over the Gutian Reservoir drainage area of 1350 km2, the precipitation of drainage area increased by 18.87%, with absolute value increased 22.4 mm, total rainfall 30.24 million m3, runoff coefficient of the reservoir 9.31%，inflow 29.95%，absolute increment 5.17 m3/s，the total inflow 13.59395 million m3. The precipitation enhancement operation improved the ecoenvironment, heightened soil moisture, and enhanced the runoff coefficient. The relative increment of inflow is larger than that of area rainfall. The economic benefit of waterstorage precipitation enhancement operation is larger than that of droughtresistant precipitation enhancement operation.