§25.975(a)(7) at Amendment 25-143 requires to prevent fuel tank explosions that caused by propagation of flames from outside the tank through the fuel tank vents. Based on the review and study on the background of regulation amending and the contains in advisory circular AC25.975-1, this paper definitudes the minimum standard for flame arrestor, the means of compliance for using flame arrestors as a means, and the concerns should been considered in verification. The research can provide guidance for design and verification on the fuel system for transport category airplane.