Abstract: As for the traditional smooth blasting of the large cross–section tunnel, it is hard to ensure that all pe? ripheral holes detonate simultaneously and there are a series of problems like low contour flatness and residual blasthole trace rate, large overbreak and underbreak, poor shaping quality and so on. Based on the East Tianshan tunnel,the blasting technique with the reserved smooth blasting layer is adopted to conduct full-face construction, and good smooth blasting effect is obtained by optimizing initiation sequence, network and parameters. The site test results show that the average linear overbreak is controlled within 15-25 cm which is reduced by 80% compared with traditional smooth blasting; the concrete consumption of primary support is reduced by 2.63 m3/m; and the parameters of practical cyclical advance rate, residual blasthole trace rate, unit explosive consumption and so on are significantly improved.