Abstract: The distribution property of σ_mises and I₁ at the double-side symmetry crack tip of the finite wide plate under uniaxial tension stress and the causes are analyzed by linear elastic finite-element method.I₁/σ_mises distribution function at crack tip is established based on the simulation results.The function is only correlated with Poisson ratio and crack length and incorrelated with plate thickness,elastic modulus and nominal stress.The function can be used to explain thick plate fracture behavior commendably.