Multi-Input Multi-Output (MIMO) radar has flexible working modes,which has shown outstanding potential in such areas as anti-interception and weak target detection.Its advantage of multiple transmission and reception signals also brings certain limitations,that is,each channel is required to transmit orthogonal waveforms.Therefore,the design of orthogonal waveforms has become a core area of MIMO radar systems.In this paper,a modified Jaya algorithm is proposed to design waveforms with constant amplitude and arbitrary phase,which display good aperiodic auto-correlation and cross-correlation properties.Based on the framework of Jaya algorithm,the crossing and mutation operators of Genetic Algorithm (GA) is incorporated into the individuals update function to design discrete-phase waveforms,and Hamming Scan algorithm is applied to find the best sequence from the output of Jaya algorithm.Numerical simulations have verified the effectiveness of the proposed algorithm.