When using microring resonators to realize group velocity control, the influences of various parameters on optical pulse transmission cannot be neglected. The parameters lead to the pulse broadening and the pulse distortion. The expressions of the second-order and third-order dispersions in single ring resonator were derived based on the transmission characteristics of the microring resonator. Aiming at the resonator without loss/gain, the pulse distortions resulted from the higher-order dispersions and the input pulse center wavelength were analyzed, during using microring resonator to realize the control of the group velocity. In addition, the influence of loss/gain on output pulse distortion of single ring resonator was derived. The results show that the second-order dispersion leads to pulse broadening and the third-order dispersion is accounted for the pulse distortion and the position of the central wavelength of the input pulse affects the depth of the pulse splitting bottom while the loss and gain affect the pulse distortion. This work provides design basis for applications of microring resonators in group velocity control.