Abstract: For a rainstorm event of the Meiyu-period in July 2014, LAPS analysis fields are compared with multi-source observation data. Data are obtained by the Mesoscale Heavy Rainfall Observing System (MHROS) over the middle region of the Yangtze River in China. Doppler radar, radiosonde and surface observation data are assimilated by LAPS of the Institute of Heavy Rain (IHR). This heavy rain event is preliminarily analyzed and simulated using LAPS fields. It is shown that the evolution of the integrated total precipitable water, the integrated liquid water and the cloud base of LAPS is consistent with the radiometer observation over Xianning site. Compared to GFS background data LAPS wind analysis is closer to observation of wind profiler radar. The vertical profiler of LAPS wind is closer to that of the troposphere wind profiler radar observation than the boundary layer one. The height of LAPS cloud analysis is close to Ka band cloud radar observation. The horizontal distribution of LAPS integrated total precipitable water is similar to the GPS/MET retrieved water vapor. The distribution of LAPS data-derived radar echo is consistent with the analysis of SWAN during the rainfall event. LAPS can depict the detailed structure of cloud, which is close to the FY-satellite infrared cloud image. Compared to GFS background field the intensity and evolution of LAPS surface analysis fields at the station of rainstorm center are both comparable to surface observation data. The evolution of LAPS analysis fields is close to the conventional radiosonde observation. For the elementary fields of Xianning site, LAPS analysis fields are closer to the GPS sounding data than the GFS background fields. According to the preliminary diagnosis of the heavy rain in the southeast Hubei using LAPS fields, the evolution and the mesoscale dynamic configuration, as well as the favorable moisture conditions of rainstorm center can be analyzed. The development of precipitation cloud can be described. From the results of the numerical experiments, LAPS can provide better initial conditions for WRF model to improve the simulation of heavy rain events.