In recent years, the Inner Mongolia Autonomous Region has established 6 sand sto rm inspection stations. A series of quantitative data, such as the instrumentm easured visibility, PM10, TSP was obtained from the continuously quantitat ive observation in the sand dust weather. It provides the basic requirement for the sand storm quantitative analysis and forecast. Ten strong sand storm process es in Inner Mongolian during 2004-2007 are chosen, and the instrument measured data of 6 sand storm inspection stations combining with the observati ons are analyzed. The analysis indicates that the instrumentmeasured data has superiority i n continuation, stability and quantification. But it is different from the view of point of the present sand weather service standard. The new grading standard is needed. Under the existing data condition, A sand dust weather grading standa rds is determined initially based on the instrumentmeasured visibilityand PM10. The quantitative condition and the mechanism of the sand storm formation are discussed. The instrumentmeasured visibility, PM10 sand sto rm quantitative prognostic equation is established on the predictor of sand dust composite index, the friction speed and so on. This sand storm forecast method is used in quantitative sand forecast in 2008 and obtained good effect.