The invention relates to a machining method of a crankshaft connecting rod neck V-shaped through-type weight reducing hole. A crankshaft is fixed on a workbench of a machining center, then the procedures of bottom hole drilling, rough boring, fine boring, forming and milling of a hole bottom transitional fillet, grinding a fillet of a cross position of the weight reducing hole, and the like are performed on the machining center, and machining of the V-shaped through-type weight reducing hole is completed. The invention not only can efficiently process the V-shaped through-type weight-reducinghole, but also can process the V-shaped through-type weight-reducing hole with good quality, etc. The invention has the advantages of simple operation, obvious use effect and the like, and is suitablefor wide-range popularization and application.