To solve the problem existing in the field of fire extinguishing for certain type vehicles for a long time, a method of spray control for extinguishing bottle is put forward. It gives the composition of a fire extinguishing system and bottleneck for function transformation. The working principle of the spray control method for extinguishing bottle is described. It also gives a feasible pressure sensor conversion value, and analyzes the technical maturity and economy of the proposed method. The test results show that the proposed method is effective, and can quickly judge when the drug of extinguishing bottle is used up, which better solve the difficult time orientation in the process of transformation function, and really realize no pause, no spacing, no delay for fire extinction.