As tunnels are integral to railways and other transport infrastructures, studying the vibration response and attenuation rule of tunnel blasting for tunnel construction projects is significant. The blasting solutions proposed in this paper are to minimize clear distance in the blasting excavation of a high-speed railway tunnel for the Chongqing-Kunming high-speed railway construction project. A new excavation method was developed to divide the excavation section into alternating blasting on both the left and right sides. Besides, the blasting vibration velocity of the double-line tunnel was monitored. The vibration velocity analysis of the advance tunnel shows that the maximum vibration velocity in the tunnel is mainly caused by cutting hole and vault auxiliary hole blasting, and the radial vibration velocity is the maximum. The vibration velocity of the arch waist of the explosion side wall is 1.3 to 2 times bigger than that of the arch foot on the cross-section, and the ratio caused by the initiation of the cutting hole is relatively small. Meanwhile, the vibration velocity of each point in front of the tunnel face is more significant than that at the relative position behind the vertical section. In contrast, the attenuation rate of the vibration velocity behind is relatively more significant. The research findings have been successfully applied to the engineering practice, and a relevant small clear distance tunnel has been safely connected.