Abstract: Sum-frequency term of the rate equation theory of passively Q-switched intracavity sum-frequency Raman laser was derived from the sum-frequency theory. Based on rate equations of passively Q-switched Raman laser, passively Q-switched intracavity sum-frequency laser rate equations were derived and normalized, and eight comprehensive parameters were obtained. The normalized expression of the peak power and the single pulse energy were derived. The influence of these comprehensive parameters on the peak power, the energy of single pulse and the pulse duration was observed by numerical simulation. The influences of each parameter were analyzed, and it was found that the sum-frequency factor and the normalized Raman gain coefficient need to be matched with each other to achieve the high efficiency output of the sum-frequency. Finally, the numerical simulation results of passively Q-switched intracavity sum-frequency Raman laser rate equations were compared with those of passively Q-switched intracavity frequency doubling Raman laser rate equations.