Using a dynamic caustics blast loading system, we studied dynamic behavior of asymmetric Y-shaped cracks propagation under blasting loading. It was found that before two opposite moving cracks encountering, their tip singular fields affected each other, the shape of caustics spots distorted and stress fields of the crack tip changed. Moreover, two moving cracks propagated along the deviating horizontal direction, and the deviation angle gradually increased. However, after two opposite moving cracks encountering, the deviation angle gradually decreased, and two moving cracks propagated along the direction of the existing crack. It can be seen that two branched cracks intersected at the main crack, and the wing crack easily initiated from the branched crack with a smaller incident angle of stress wave and a longer length, and propagated along the vertical direction of the maximum tensile stress. However, this kind of branched crack may inhibit the propagation and the stress intensity factor of the branched crack with a larger incident angle and a shorter length. The average values of dynamic stress intensity factor of the branched crack decreased with the increase of the incident angle of stress wave. In addition, the propagation velocity of the branched wing crack presented oscillating change law. Therefore, the results provide a reliable basis for the analysis of crack propagation in practical engineering.