A high order of asymptotic solution of the singular fields near the tip of a mode III interface crack for pure power law hardening bimaterials is obtained by using the hodograph transformation. It is found that the zero order of the asymptotic solution corresponds to the assumption of a rigid substrate at the interface, and the first order of it is deduced in order to satisfy completely two continuity conditions of the stress and displacement across the interface in the asymptotic sense. The singularities of stress and strain of the zero order asymptotic solutions are −1/(n1+1) and −n/(n1+1) respectively (n=n1, n2 is the hardening exponent of the bimaterials). The applicability conditions of the asymptotic solutions are determined for both zero and first orders. It is proved that the Guo-Keer solution [23] is limited in some conditions. The angular functions of the singular fields for this interface crack problem are first expressed by closed form.