The heavy rainfall process occurred on 3 August 2005 in Beijing is analyzed in detail by means of the Airda3000 boundary wind profiler data from three stations in the Beijing urban and suburb areas. Results show that about 10 or more hours before the process started, there appeared doubled lowlevel jets, which had a complex structure with multiple centers. The wind profiler data show that the process had a complex vertical structure, the main mesoscale system of which was a vortex on the shear line induced by a highlevel trough and weak cold air; the surface wind convergence in the urban area started several hours before the heavy rainfall (nighttime); and the upward propagation of the convergence (shear) layer began at the beginning of rainfall, which was helpful to the development of the process.