"Photon Switching by Quantum Interference" which was proposed by Harris and Yamamoto in 1998[1] introduced a four-state atomic system that an additional light field besides the three-state EIT[2] system was added to destroy the quantum interference of EIT system. The scheme and theoretical study were introduced in it. And in this thesis, we go a step further to theoretically study this optical switches utilizing storage and retrieval light pulses[3]. We found that the theoretical prediction did not match the experimental results properly, hence the study of how to revise it was developed. The required theoretical analysis equation and simulation results are all involved in this thesis.