The invention discloses a differential protection y-side phase-shift current phase compensation method for a YNy8 transformer. Y-side and y-side of the YNy8 transformer eliminate zero-sequence current in phase current to prevent misoperation due to influence of zero-sequence current on differential protection of the transformer. For differential protection of the YNy8 transformer, the phase compensation employs a y-side phase shift method with the Y side as the reference, wherein the current phase compensation for Y side is conducted through a calculation method of eliminating zero sequence current by sequence phase current with the A-phase current as the reference, and the y side of the YNy8 transformer employs a calculation method of eliminating zero sequence current by sequence phase current and conducts current phase compensation by the principles of same phase with Y-side corresponding current. The method is applicable to software phase compensation for current of longitudinal differential protective devices of YNy8 wiring transformers with various voltage levels of substations of a power transmission and distribution network. The method is simple and clear and is easy to realize.