The invention discloses a method for adjusting a die plate in prefabricating of a curved immersed tube. The method comprises the following steps: 1) propping and adjusting a bottom die to be horizontal, and then propping an overturning plate until reaching the same height as the bottom die; 2) transversely pushing a side die to a designed position; accurately positioning; returning; and measuringagain after a reinforcement cage is propped and pushed inside; 3) adjusting the height and axis position of an inner die; returning the inner die after adjusting; and measuring again after the reinforcement cage is propped and pushed inside; and 4) hoisting a bottom plate, a wall body and a top plate by blocks in sequence during mounting an end die; and measuring and positioning each end die in order to ensure the size of the end surfaces of immersed tube sections. According to the method, the curved immersed tube is prefabricated through an existing linear die plate; and moreover, the requirement on the prefabricating accuracy of the curved immersed tube can be met, and a manufacturing die plate specially designed for the curved immersed tube is avoided, so that the prefabrication construction cost of the immersed tube can be decreased; and the method is of important guiding significance on design and construction of similar immersed tube tunnel engineering.