This paper deals with the nonlinear quasi‐fracture behavior of polymers. Using the finite element method, the quasi‐fracture model composed of an isolated craze opening with a nonlinear boundary envelope forces represented by oriented fibril domains is analyzed in simply‐stressed rectangular plate. The stress distribution, the displacement profile, as well as the yield or plastic or flow zone adjacent to the craze tips are obtained. It is found that the variation of the stress distribution near the craze tip is not as sharp as that for an elastic crack. The initial load required for yielding or flowing is greater for the quasifracture as compared with that for a classical fracture. Under the same load the yeild or flow zone is somewhat smaller as compared with that obtained on the basis of linear elastic‐plastic fracture mechanics theory.