A mathematical derivation was carried out about dynamics of the interaction between single photon and cavity-quantum dot system model and the mutual conversion was realized between the stationary qubit and flying qubit by numerical stimulation. The results show that the photon emitted from the cavity-quantum dot system is a smooth wave packet. By changing the parameters such as laser pulse time, the entanglement between photon and atom in quantum dot can be realized, which is the basis for realizing the entanglement between atoms in different quantum dots. These results are important to solve such hot problems as the construction of interface of quantum computers based on cavity-quantum dot system, preparation of entangled states and realization of controlled gates in the system.