By means of the conventional meteorological data,digitized infrared satellite imagery andthe radar echoes, the developing characteristics of the mesoscale convective cloud clusterswhich caused the cloudburst over the northern Fujian in 18 - 19 June 1998 were analysed,andthe effect of the wet-baroclinic front zone and the southwest jet flow in low altitude on themesoscale convective cloud clusters were discussed. Some features of cloudburst during thedeveloping were given.