In this study, a higher order asymptotic expansion of anti‐plane crack tip fields is investigated for dynamic transient crack growth. A six term and a three term expansion for the shear stresses around the crack tip are obtained for cracks propagating at constant and nonuniform velocity, respectively. In order to compare with the near tip field solution derived in this study, an exact transient solution of propagating cracks with constant velocity is examined. The result shows that the use of the singular field to represent the actual stress field should be carefully considered, especially in the early stages of the dynamic transient field.