Aiming at the problem that traditional Direction of Arrival (DOA) estimation methods cannot process multiple sources with high accuracy while improving Degree of Freedom (DOF)a new two-dimensional DOA estimation method for MIMO radar based on the coprime array (SM-MIMO-CA) is proposed.This method is based on a new MIMO array-based coprime array model (MIMO-CA)which improves the accuracy of multi-source estimation when the number of elements is finiteand a larger array aperture is obtained with a smaller number of elementswhich improves the accuracy of two-dimensional DOA estimation.Finallythe effectiveness and reliability of the SM-MIMO-CA method in improving DOF and improving DOA accuracy are verified through experiments.