Abstract: Disaster-causing factors are the prerequisites for the occurrence of disasters. Importance analysis and hazard assessment of rainfall disaster-causing factors are crucial for preventing rainstorm disasters. Based on precipitation observation data from 66 national meteorological stations from 1981 to 2020 and 1 038 provincial meteorological stations from 2010 to 2020 in Fujian province, the correlation coefficient method was used to calculate and compare the weight coefficients of the rainfall disaster-causing factors of non-typhoon rainstorms in different seasons and typhoon rainstorms in different periods. Then, the comprehensive index method was employed to conduct the hazard assessment and validation of non-typhoon rainstorms. The results are as follows: (1) The spatial extent of heavy precipitation is the most critical factor in causing disasters for non-typhoon rainstorms in all seasons and for late-season typhoon rainstorms. Short-duration intense precipitation is the major factor contributing to summer rainstorms, early typhoon rainstorms and typical typhoon rainstorms. (2) The results of the disaster risk assessment of non-typhoon rainstorms show that the hazard of the non-typhoon rainstorm process from June 14^th to 26^th in 2010 was the highest. There is an overall spatial with two contiguous high and very high risk areas in the northwest inland and southeast coastal areas respectively. (3) The spatial distributions of disaster risk for three historical non-typhoon rainstorm processes from 2010 to 2020 obtained based on the assessment model are basically consistent with the disaster situation.