Abstract: The extreme persistent hazard rainstorm from 3th August to 4th August of 2012 was analyzed in this paper using the convectional observations, FY-2E satellite data, the data of automatic weather stations and NCEP FNL reanalysis data. The results show that the joint actions of "three zones" system of tropical, subtropical and westerly zone induced the rainstorm event. The stable maintaining of subtropical high leads to the water vapor and energy of three typhoons transport to Liaoning and provides sufficient conditions of the warm and moist air. The divergence zone in the right rear of high level jet stream and the convergence zone of low level jet stream superpose in western Liaoning for a long time, which induces the development and maintaining of dynamic ascending motion. Meanwhile, long-time maintenance of the inverted trough of typhoon in Liaoning leads to the slow movement of strong precipitation area. The Okhotsk high makes the westerly zone and the polar cold air influence Liaoning mutually. The warm and moist air and the cold and dry air convergences are maintained in Liaoning. As a result, the persistent symmetric instability and the rapid reconstruction of the convective instability contribute to the continuous development of the mesoscale convective cloud cluster that leads to the formation of persistent heavy rain.