In order to obtain absolute phase of spatial discontinuous object surface quickly, a phase unwrapping method based on encoding grating is proposed. In this method, a grating fringe image with encoding information is projected, the fringe order information which is needed for phase unwrapping is obtained, and then the absolute phase information of the whole measured surface is obtained. The three-dimensional information of the whole measured surface is obtained according to the phase-depth relationship. Compared with the phase unwrapping method based on the Gray code, the proposed method does not depend on gray information of the measured object and has better noise resistance. Only one additional encoding fringe is needed for the proposed method, so it is more suitable for three-dimensional measurement with high real-time requirement. The effectiveness and feasibility of the proposed method is demonstrated by experiments.