According to the characteristics of cumulus and stratiform clouds during the meiyu period (plum rains) over Jianghuai valleys (the Changjiang (Yangtze) River and the Huaihe River), a modified Kuo-type cumulus parameterization scheme applicable to midlatitude con-vective systems is suggested in this paper. It is often observed that cumulus and stratiform clouds coexist in a rain-bearing synoptic systems and the precipitation amount associated with this system may be amplified by their interaction. With some important processes of cloud physics taken into account, we use a simple seeder-feeder model (including colloidal instability, collision effect and entrainment) to describe this process of interaction within framework of Kuo-type cumulus parameterization. It is found that the rainfall amount caused by ice crystal effect accounts for 30-40% of total rainfall, but the collision effect is not so great generally. We introduced this scheme to the regional numerical model used by Wuhan Observatory of Hubei
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