A simplified one-and-one-half-dimensional,time - independent warm cumulus model is given after simplification and adjustment of the relevant dynamical and physical equations accounting for the main meso- or intermediate-scale characteristics of the cumulus clusters on the Meiyu front. Radiosonde data for Nanjing and Xuzhou in 1982 were fed into the model. The distribution with altitude and variation with time of such parameters as vertical velocity,temperature,specific humidity and water content in cloud as well as precipitation amount and density,radii and falling velocity of raindrops were calculated. Investigation into the evolution and macro and micro structures of rain clouds in the Meiyu are then made on this basis .Thepossibility of estimating the rainfall amount and intensity in the Meiyu front with the cloud model is discussed.