A torrential rain event with severe secondary disasters(e.g., debris flow) occurred in the western Sichuan Basin during 18-19 August 2010.Based on numerical simulation data and 0.5°×0.5°four-times-daily reanalysis data from the NCEP's Global Forecast System products, combined with dynamic parameters including the generalized vertical convective vorticity vector(cvz^*), mass divergence(divden), vertical helicity(hel), mass vertical helicity(helden), moisture vertical helicity(helqv), thermal vertical helicity(helth), moist thermodynamic advection parameter(mtp), mass divergence flux(wdiv), divergence flux(wdendiv), thermal vertical divergence flux(wptediv), moisture divergence flux(wqvdiv), generalized Q vector divergence(divq^*), a diagnostic analysis and forecasting study of this torrential rain event were carried out.The results showed that:(1) all twelve dynamical parameters showed strong signals in the torrential rainfall area.(2) The curves of the temporal trends of regional average dynamic parameters and the mean regional rainfall were similar, showing a twin-peak structure.The time series' correlation coefficients of the mean regional rainfall and the regional average values of generalized Q vector divergence, moisture vertical helicity(helqv), thermal vertical helicity(helth), mass vertical helicity(helden) and vertical helicity(hel) were greater than 0.9.(3) The dynamic parameters considered in this study are of considerable importance in the diagnosis and prediction of torrential rain in this region.