A garment three dimensional tailoring method is disclosed. A tailoring operation method includes the following steps: taking a common cloth, marking basic reference lines including a front central line, a back central line, a waistline and a hipline of a human body; allowing a guest putting on a matched knitted corset to stand with a correct gesture, allowing the prepared cloth with the basic reference lines of the step 1 to face basic lines of all parts of the human body, fixing a front sheet and a back sheet from a side neck point to a shoulder point by straight pins; fixing bust lines, waistlines and hiplines at two sides of the human body by straight pins; folding a bust dart and a waist dart at proper positions according to a design demand and differences of the human body, and fixing the bust dart and the waist dart by straight pins; determining a reference neck hole and sleeve holes on the cloth according to changes of the design and the human body; adjusting details of all parts to achieve a human body correction effect, and using a pen to mark dart paths, dart positions and dart values at the places fixed by the straight pins so as to provide references for a template making worker; taking off the cloth, and making a corresponding neck template and sleeve templates according to the reference neck hole and the reference sleeve holes determined on the human body; making a temperate of a cloth body according to markers on the cloth; and processing the clothe into a ready-made garment.