Abstract: Waterlogging disaster data from 2016 to 2022 and hourly precipitation data from 110 meteorological observation stations in Nanchang were used to analysis the characteristics of waterlogging disasters,as well as the critical value of the rainfall index of different water depth was determined. Then, combined with the disaster-bearing body conditions,the prediction level of waterlogging meteorological risk was furthter established. Moreover, the water depth estimation model was constructed based on the random forest algorithm.Finally,pre-assessment of urban waterlogging risk was carried out and the accuracy of risk level forecast was tested by using the typical cases. The results are as follows. (1) The monthly change of waterlogging disaster demonstrate unimodal distribution with a peak in June.The daily change demonstrate bimodal distribution with two peaks at 09:00 BT and 16:00 BT respectively. The disaster points are concentrated in the core urban area. (2) Water depths above 50 cm in Nanchang are primary caused by short-duration heavy rainfall or rainstorms. It is easy to cause the water depth of more than 50 cm, when 1 h rainfall > 40 mm, 3 h cumulative rainfall > 78 mm, 6 h cumulative rainfall > 98 mm, 12 h cumulative rainfall > 123 mm or 24 h cumulative rainfall > 135 mm. (3) The average accuracy of the training and tests was 96% and 79% respectively. The meteorological risk of waterlogging is divided into low, medium and high levels according to the estimated range of 10, 25) cm, 25, 50) cm, ≥50 cm combined with the population and GDP conditions. (4) The estimated accuracy rate of waterlogging points in the two rainstorm processes in Nanchang are 67% and 56% respectively. And the 27 waterlogging points estimated 1-3 h in advance are all within the estimated risk area.