Abstract:Based on meteorological observational data of seven years and the pattern of sand dust weather process affecting Dalian,t he characteristics and forecast model of sand dust invading Dalian were analyze d．The results show that sand dusts in Dalian occurred frequently in spring, si milar to other sites of China. There were four source locations and three transp ort paths of sand dust. The mean relative humidity was very low and the wind di rection was northwest mainly in sand dust weather. Most of the sand dusts move along the northwest paths invading Dalian.The north path corresponds to three w eather patterns, the west path corresponds to other three systems and the northw est path to four systems. Theforecast of sand dust should pay more attention to the sand rising in upstream region, then combine with analyzing the forecast m odelof three transportation paths.