The invention belongs to the technical field of oil exploration, development and augmented injection, and particularly relates to a micro-fracturing augmented injection process method suitable for a water injection well of an offshore oil field. The micro-fracturing augmented injection process method comprises the following steps: S1, based on the limit displacement, a procedure for testing a pre-pressure water absorption index is established, the pre-pressure water absorption index of the water injection well is calculated, and a pre-pressure water absorption indicative curve of the water injection well is drawn; S2, according to the water absorption index and the limit displacement, fracturing working fluid is injected into a target formation through a step-type progressive increase pump, and a fracturing construction curve graph is drawn; S3, according to the fracturing construction curve graph, micro-fracturing breaking points are judged, and after the breaking points occur, the pump is stopped; and S4, a post-pressure water absorption index of the water injection well is tested, and a post-pressure water absorption indicative curve of the water injection well is drawn and compared with the pre-pressure water absorption indicative curve of the water injection well to evaluate the micro-fracturing effect of the water injection well. The micro-fracturing augmented injection process method has the beneficial effects that the material cost of acidification deblocking and the cost of fresh water transportation are saved, important significance for low-cost efficient augmented injection of the offshore water well is achieved, and the effect of relieving a near-well damage belt is obvious.