Abstract: By means of Christian network with Xu Guangqi as the core,Sun Yuanhua acquired western mathematical knowledge and firearm technology. With the support of Christian network,Sun Yuanhua made important contributions to the firearm technology in late Ming Dynasty. Sun Yuanhua established Dengzhou Firearm Camp, imported western firearms,western learning and western soldiers;set up first western style firearm force of China. He greaty promoted the development of firearm technology in late Ming Dynasty. On practice of firearm technology, Sun Yuanhua wrote Xi Fa Shen Ji. This represented the highest level of firearm technology in late Ming Dynasty,and gave a full description of western firearm technology. Xi Fa Shen Ji is a milestone in the field. Sun Yuanhua deserves attention and research.