Abstract: The equations determining rubber constitutive model and evaluating the model are derived by application of the finite deformation theory of rubber, test data and the least square method. According to the compressive test data of packer elements of two acrylonitrile-butadiene rubbers（No.701 and No.29）, the above equations are used to determine the suitable models of two-, three-, five- and nine-constant Mooney-Rivlin(M-R) models and three-power constitutive model, and the evaluation and comparision of error are done. The results show that the three-power Yeoh constitutive model is suitable for the test data of the material No.701 and No.29 but the twoconstant M-R constitutive model is improper because of big errors. The material No.701 should use the five- constant or up M-R constitutive models. The material No.29 should use the three- constant or up M-R constitutive models.

Key words: packer element, acrylonitrile butadiene, constitutive model, MooneyRivlin, Yeoh