To obtain an accurate polarization scattering matrix, simultaneous full polarization radar systems must transmit two signals. The performance of orthogonal polyphase codes designed by the traditional method is limited by the code length and is sensitive to Doppler frequency. In this paper, we propose a design method for orthogonal polyphase codes that have good Doppler tolerance. We consider the peak sidelobe level and isolation and transform the signal design problem into a nonlinear optimization problem, which we solve using a genetic algorithm. Our simulation results show that our proposed orthogonal polyphase codes have better Doppler tolerance and their peak sidelobe levels and orthogonal performances are 1.5～2 dB better than the codes designed by Deng or Khan. As such, the new design can improve the measurement accuracy of simultaneous full polarization radar systems.