Abstract: In this paper, hardstorm rainfall processes in north-China induced by a landed northward moving and decaying typhoon axe analysised. It is shown that under the interaction between synoptic systems of the mid- and low-latitude belts, the hard rainfall bearing systems possess semi-tropical characteristic. The characteristics of the semi-tropical cyclone and semi-tropical front are discussed and the difference between the continental and oceanic semi-tropical cyclones is pointed out. Finally, it is emphasized that futher studies of semi-tropical synoptic systems are of great significance.