Based on the current experimental conditions, a model of annular four-level semiconductor quantum dot electromagnetically induced transparency medium is constructed by considering the phonon-assisted transition effect in semiconductor quantum dot. Dynamical behaviors of the temporal optical soliton in this system is analytically studied by using multiple-scale method. The results show that dynamical properties such as amplitude, width and group velocity of the temporal optical soliton can be controlled by adjusting the strength of the phonon-assisted transition. The group velocity of the temporal optical soliton is much smaller than the velocity of light. And when the strength of the phonon-assisted transition increases, the group velocity of the soliton decreases continuously. So, the group velocity may slowly close to zero that it appears stagnation. The optical stagnation is helpful for light storing in quantum devices. It provides some reference values to realize optical storage in the semiconductor quantum devices.