Abstract: A new method,based on the theory of mathematic statistics,is constructed to analyze the crude oil migration trends.A good deal of indices tracing crude oil migration trend are characterized as a parameter: migration index(I_m).Contour maps by Im can figure the direction of oil migration.A reliability parameter(K)which is used to judge the credibility of the results is also defined in this method.Concentration data(66)of polar compounds,maturity parameters(13)and isomer ratios(15)of polar compounds of Ordovician crude oil samples(22)from the Tahe Oil Field were analyzed respectively.The results show that crude oil migration directions are from east to west and from south to north.Compared with the K values of the three groups of parameters,the Im of polar compound concentration can indicate the direction most accurately.