Base on the principle of nonlinear calculation, the mechanical models and the method of models experiment, we have provided a numerical analysis method of fitting hyper-elastic material constitutive relations. The method educed material spacial constitutive relations expressed by tensor through strain energy theory. After that, deduced material uniaxis constitutive models and use BP neural network to fit coefficients. Constitutive relations are the base of material deformation research. However we just paid attention to deformation experimental result before, rather than theoretical analysis. The theoretical analysis method this paper researching is convenient and precise and scientific, so it has theoretical meaning and practical value.