Abstract: The results indicated that the typical black storm and severe sand-dust storm in the Northwest Region wereg enerated and developed under an interaction between the special large scale circulation pattern and meso scale systems,the severe cold front with intensive front zone on mid-and lower-levels moved along a huge of desert with abundant sand source to be a necessary condition for a black storm and a severe sand-dust storm.In order to study the mechanismon the formation and transpo rtion as well as sedimentation for sand-dust of the black storm and sand-dust storm,a parameter ized scheme of sand-dustsource and sink term and an equation of transporting sand-dust were achieved and posed,while both the scheme and the equation were introudced to the meso scale model and simulation system for MM4 which have been done.