A medical imaging system and a medical imaging method thereof are provided. The medical imaging method comprises the following steps: acquiring an ultrasound image and a photoacoustic image and performing an image overlaying process on the ultrasound image and the photoacoustic image, so as to obtain an overlaid image.一種醫學成像系統及其醫學成像方法。所述之方法包括下列步驟:取得一超音波影像以及一光聲影像;以及將超音波影像與光聲影像進行疊合處理,據以產生一疊合影像。S302、S304...步驟