A new method based on phase tracking algorithm and ray tracing algorithm is proposed for measuring the three-dimensional (3-D) shape of object in water. It uses digital sinusoidal fringe to record the information of object's 3-D shape. The phase tracking is taken to define the according points in the deformed pattern captured by the camera and the fringe pattern projected by the projector. Then the object's 3-D shape is calculated with ray tracing algorithm. This method uses 2-D patterned fringe to obtain the 3-D shape of object and the scanister is not needed, so the speed of reconstruction can be greatly increased and the cost of instruments will descend. An actual measurement is done, the perfect results of the reconstructed shapes prove its correctness and feasibility.