In order to provide best parameters for unstable ring resonators with reverse-wave-suppressor (RWS), it is necessary to make numerical simulation. With the help of the self-consistent-equation, Matlab computation results show that RWS can increase the output of forward wave and suppress the reverse wave in unstable ring resonators, by changing the parameters such as the length and magnification of resonator. When forward wave and reverse wave compete for the same particles, which is caused by Doppler frequency shift, suppression ratio of RWS gets high while forward wave output declines. To a certain resonator, a best magnitude can be got to provide the best output amplitude. Results show that introduction of RWS can increase the output of unstable ring resonators. All these computational results are useful for practical unstable ring laser design.