Abstract: This paper has computed single relation between the variation of westerlies index day by day in 60- 140°E.40- 50°N(45°N) range and the variation of qeopotenti’al height next day in 120°E.130°E, 140°E for 25-35°N range. The result shows that there existed no relation between the variation in near past (130°E, 140°E) of main body for northwest Pacific subtropical anticyclone and the westerlies index. On the contrary, it shows that they are independent of each other and have regular relation in edge region (120°E). Analysis shows that the relation between the variations of the subtropical anticyclone and the midlatitude westerlies index may be quite complex. Roughly speaking, there are two cases.One is contrary variation, and the other is coupledvariation. Therefore it is improper using the variation of system in westrlies to pr-edict the variation tendency of subtropical anticyclone.