Abstract: During the Jiajing Reign of Ming Dynasty, the invasions by Japanese pirates in Fujian continued. However, the garrison troops were gradually weak, which led to the establishment of the Military Camp System. A hundred years later, the camp affairs fell into disarray, showing signs of decline. Military Camp Affairs was compiled by WANG Jiaxiang. The book detailed many shortcomings of the Fujian camp system during the Chongzhen Reign in terms of economy, system and military operations. It also proposed corresponding reform strategies. Ten new tactics for firearms were also created, which could be deployed for ambushes, attacks, and defenses in both plains and mountainous terrains. Among them, the Three-tiered Attack Formation shared similarities with contemporary European linear tactics. However, the shooting power of early guns could not replace the impact force of cavalry, showing a trend of integrated development. This led to the development of the "Nine Guns Three Charges" or "Three Guns One Charge". The guns provided a combat mode into which cold weapons and hot ones were combined. By examining the old problems and new formations of the Fujian camp system, a new perspective can be provided for further explanation of the reasons for the fall of the Ming Dynasty. The examination also elaborates the use of firearms in the late Ming Dynasty, and the transformation of military thought in Ming Dynasty.