A novel scheme of photonic aided vector millimeter-wave(mm-wave)signal generation without a digital-to-analog con-verter(DAC)is proposed.Based on our scheme,a 20 Gb/s 4-ary quadrature amplitude modulation(4-QAM)mm-wave signal is generated without using a DAC.The experiment results demonstrate that the bit error rate(BER)of 20 Gb/s 4-QAM mm-wave signal can reach below the hard-decision forward-error-correction threshold after a delivery over 1 m wireless dis-tance.Because the DAC is not required,it can reduce the system cost.Besides,by using photonic technology,the system is easily integrated to create large-scale production and application in high-speed optical communication.