In order to improve the light fusion speed in multi-projector display system, a multi-projector display fusion method based on modulation information of structured light fringe is proposed. In this method, camera is used to capture the structured light fringes on the display wall which are projected by projectors, and then the modulation information for every projection channel is calculated. Meanwhile, the sub-pixel mapping relationship between projector and camera can be built by the phase of structured light fringes. With the above relationship, the modulation value for every pixel on projector can be obtained. Using both the modulation value and the edge blending results, we can generate the final sub-pixel fusion mask for each projection channel. The proposed method has the advantages of convenient operation, fast measurement speed and free of ambient light interference, and it has a wide application field. The theoretical analysis and real scene experiments both validate the effectiveness and feasibility of the proposed scheme.