Abstract: The paper aims to improve the quality of short-time rainstorm early warning, and to exert the role of early warning signal in disaster prevention and mitigation. The release condition of rainstorm warning signal for a local short-time rainstorm on July 15, 2014 in Liaoning Province was analyzed. During this short-time rainstorm process, the rainstorm warning signal accuracy in Liaoning Province was 83.3% on the premise of accuracy on village and township level, and the schedule advanced 37 min on average. But the time of red and orange signal for heavy rain was shortly ahead, respectively for 10 min and 20 min. Forecasters on duty should deal with the rainstorm warning flexibly based on correct understanding of the early warning signal issuing rules, and seize the best opportunity for releasing rainstorm warning signal and provide a good forecast service. Besides, through the analysis of the cause of the rainstorm process, this rainfall had smaller scale feature obviously, and appeared more suddenly and powerfully. But, it was not easy to analyze on large scale weather system, for the potential instability, and the southeast and southwest low level jet were the main causes of the rainstorm.