A new all optical wavelength converter (AOWC) using single port coupled semiconductor optical amplifier (SOA) based on cross gain modulation (XGM) was brought forward, and a dynamic model was presented. Based on the dynamic model, factors which affect converted signal chirp, such as signal power, probe power, output extinction ratio, input extinction ratio, were analyzed respectively. The numerical result shows that converted signal chirp decreases in some extent when using this kind of wavelength converter.