_{Non-electric initiation system was the only initiation system for viaduct blasting demolition. Aimed at the application actuality, the relay point characteristicof multiple parallel detonator initiation system was studied in the paper, and the simple formula for mean value of the relay point initiation time was put forward. Reliability standard for non-electric initiationsystem of different scale was established. Duplex-cross non-electric initiation systemwas invented, which not only can avoid side roll in the viaduct collapse process, but also can elevate the reliability of the relay point. Research achievements can provide theoretical basis for viaduct blasting demolition initiation system design.}