The orthogonal signal design is one of the key technologies in the radar signal generation technology under the background of MIMO. In order to reduce the complexity of design and improve the performance of radar, a new method based on genetic algorithm is adopted. The method utilizes the strict orthogonality of Hadamard matrix. Firstly, a kind of Hadamard matrix is constructed, and the initial code sequence is selected. Then, the “and signal” is used as the cost function, and the genetic algorithm is used to solve the approximate optimal signal set. The algorithm is implemented by Matlab. The simulation results show that the method can ensure the low autocorrelation sidelobe and low crosscorrelation sidelobe, at the same time, it can ensure the signal designed to meet the strict orthogonality.