Abstract: Propagation law and overpressure load of blast wave in urban complex environment are simulated and analyzed using LS-DYNA3D software and the ALE method. Numerical simulations of blast wave propagation both in a double-building model and a single-building model are carried out. A comparison of numerical results showed that the blast wave in the double-building model might be amplified due to multiple reflections between the two buildings during blast wave propagation. Therefore, the influence of adjacent buildings must be considered when calculating the overpressure load of blast wave on the building in urban complex environment. Blast wave propagation in a typical T-type street is also simulated and the results are compared with that in the simple environment, i.e., without any buildings in the street. It is shown that the blast wave in an urban street might be strengthened due to multiple reflection by ground and surrounding buildings. When the ratio of the height of surrounding buildings to the street wide is in certain range, the amplification factor of the overpressure load will increase as the street is becoming narrower and the surrounding buildings are higher. As a result, the influence of the surrounding buildings must be considered when investigating the propagation law and blast wave overpressure load in the urban complex environment. This study provides a reference for working out blast prevention measures for large and important buildings in urban.