We extended the method of Eshelby et al.for treating a static straight dislocation in infinite anisotropic medium, to compute the elastic field of a dislocation uniformly moving on the phase boundary of a two-phase medium. The simple theory proposed in this paper is applicable in general, and can be employed directly to investigate the behavior of a tranformation dislocation in high speed motion on phase boundary, and therefore be helpful in understanding the role played by the motion of transformation dislocation in diffusionless phase transformation. Finally, the method used in this work and the discontinuity appeared in the computed field are discussed in brief.