The heavy rainfall area and maximum precipitation point were located in the southern Hainan Island during Typhoon Haiyan (1330). The causes of heavy precipitation are analyzed by using the intensive automatic weather station data, Doppler Radar data in Sanya and 025°×025° ERAinterim reanalysis data, and the WRF model is applied in the simulation experiment. The results show: (1) The easterly or southerly winds on the periphery of the typhoon were orthogonal to the southoriented Γshaped topography in the Wuzhi and Diaoluo Mountains while moving northward nearby the southern Hainan Island, and the multiple βmesoscale featured shear lines and cyclonic convergences were observed by the intensive automatic weather station and Doppler Radar in the Wuzhi Mountain and Maogan Village, where had an obvious wind direction convergence. The ground convergence center was basically consistent with the strong hourly rainfall area. (2) The local rainfall enhancement of Maogan Village was a result of interactions of the increasing of vertical velocity by the Γshaped topographical lifting, formatting of βmesoscale horizontal and vertical circulations, developing of boundarylayer convergence and upperlevel divergence. (3) The simulated strong precipitation area and extreme precipitation distributions of Haiyan were basically consistent with the observations, but the amount was less. The complex topography has positive (negative) contributions to rainfall increase (decrease) in the windward (lee) slope of mountains. It is easy to produce the βmesoscale convergence in Wuzhi Mountain and the south side of the Γshaped topography.