Abstract: In order to develop initiating technique with an initiation network used in urban's complex environment,an optimum network design and reliability research on blasting were performed.The connection method of initiation network includes double main in the first stage,bunchy connection and closed loops with four-vent of small reseaus.This connection system makes the whole blasting region form an across connection-mixing network in which double main,multiple small-net with closed loops are connected among nonel-tube detonators,and electro-detonators are initiated by multiple spots.It can greatly raise connecting speed of a network and the reliablility of initiation.By means of an illustration,some system diagrams showing different numbers of initiation points are given;and on the basis of reliability theory and the largest route principle,the reliability of every initiation system is analysed and discussed.The study results show that the initiation system is not only accurate,reliable and safe in initiation and unlimitative in initiation charges and number of detonators,but also its operation simple,detection convenient and construction period short;thus every thousand nonels can be initiated by two or three initiating spots.