The invention relates to a method for calculating the equivalent coefficient of the overpressure explosive amount of shock waves discharged into a tunnel through explosion in a structure. The calculation method comprises the following steps: step S1, carrying out explosion tests in the structure for N times; S2, according to the Delta P obtained in the step S1, calculating the equivalent quantityOmega required for generating the same overpressure P at the same position under the explosion condition of the central part of the opening end of the tunnel; and S3, setting a quantity equivalent coefficient to be Omega/Q, wherein the Q is an experimental quantity and is obtained by dimensional analysis: S4, fitting the experimental data and calculation data corresponding to the experimental datato obtain an equivalent quantity specific expression. According to the invention, based on the explosive loading capacity Q, the tunnel equivalent diameter D, the burst center height H, the matrix compressive strength sigma c and the structure reinforcement ratio Rho, the quantity equivalent coefficient of shock wave overpressure discharged into the tunnel is directly calculated when the structure explodes, and the distribution rule of explosive energy can be quickly and accurately judged by utilizing the coefficient, so that the damage of tunnel engineering is reasonably estimated.