In order to improve the quality of tunnel blasting and reduce the disturbance to surrounding rock during blasting construction, it is necessary to carry out optimization research on the original blasting scheme. Taking the parallel guide tunnel of a railway project as the engineering background, more reasonable blasting parameters are determined by using the empirical formula to calculate the powder factor, the number of holes and the parameters of each hole, aiming at the problems such as serious over-under excavation, poor working environment and slow construction progress. The number of medium and large diameter empty holes in the original blasting scheme is changed from 8 to 2, and the layout of cut holes is adjusted to provide better free surface for subsequent holes. At the same time, the orifice of the charging structure is blocked by water bags, which reduces the concentration of dust and harmful gases in the tunnel after explosion. The results show that the average linear over excavation can be reduced from 0.2~0.4 m to 0.15 m with smooth working face and bottom by using the optimized blasting scheme. At the same time, compared with the original scheme, the number of holes and the amount of explosives used in each cycle can be reduced by 37 and 49.2 kg, respectively. In addition, the construction time can be saved by 1.1 h and the cost is about 800 yuan, which has a relatively significant technical effect and economic value, and also verifies the feasibility of the optimized blasting scheme.