We tried to clarify the crystallization mechanism of long chain polymers in solution under shearing stress using polyethylene. From the bright and dark field electron microscope observations and the electron diffraction study, we demonstrated that the resulting fibrous crystals consist of the central threads with an extended chain character and the lamellae with a folded chain character nucleated on the threads. The measurements of thermal and mechanical properties gave the additional confirmation for this suggestion. From these results we discussed the crystallization mechanism on the fibrous crystals.