The sandbodies of delta and turbidite fan have been distinguished with the dispersal map of grain size parameters. It is indicated that the skewness and standard deviation are effective parameters in distinguishing the origin of the sand-bodies. In view of the limitation of B. K. Suku's discriminant in distinguishing the origin of the sandbodies for fualt-depressed lacustrine basins

the author have established a new discriminant function with grain size parameters

and gained a satisfying result.