Abstract: A triple nested High resolution Limited Area Model (HLAM) is recently developed and runs on computer CYBER-992. The model’s domain, geographical location, lateral boundary width, especially horizontal resolution are highly flexible. A case of heavy rain is simulated using this model with horizontal resolution of 50 km. The results are encouraging: (1) The location of low pressure centers, the area of heavy rainfall and the trend of rain-band are more closer to those of analysis as compared with low resolution nested grid model. (2) Although the area of high resolution model’s simulation is reduced, the forecast effect is not influenced and 48 hour forecast still has high precision. Preliminary experiments show that HLAM can be developed into a regional high resolution model for mesoscale research and operational forecasts.