The effect of blast wave with different duration on building structure and protection engineering are obviously different, long duration blast wave is generally essential in experimental studies and numerical simulations. However, it is difficult to prolong the duration of the positive pressure in the practice experiment of studying the structural responses under long duration blast load. A multi-point delayed detonation model with multiple small charge TNT explosives in a long tube explosion chamber is established by computational fluid dynamics software AUTODYN. The propagation law of blast wave in the long tube is analyzed. On this basis, the influences of length of explosion chamber, the delay detonation time and the initiation sequence on the blast wave form are further investigated. The results show that, as the distance increases, the peak value of overpressure decreases and the duration of positive pressure increases. The overpressure time-history curve with full and continuous attenuation of the wave form can be obtained by selecting the delay detonation time rationally according to the amount of explosive and the length of the explosion chamber. Detonating from the bottom of the explosion chamber and controlling the delay detonation time interval reasonably can form a long-duration blast wave which is equivalent with the continuous attenuation produced by a large equivalent charge long distance explosion. The parameters such as the length of explosion chamber, amount of explosive and delay detonation time are adjusted repeatedly, and the detonation schemes of 100 ms explosion duration and 200 ms explosion duration are provided, providing technical support for design of long duration explosion simulation device.