This paper is mainly to study the flow field and aerodynamic characteristics of a double delta wing with sweepback angles of 76°-40° at
high angles of attack under static and dynamic conditions by water tunnel
testing. The flow visualization results show that under static condition, the left and right vortex breakdown points are basically symmetrical at zero sideslip angle. As the angle of attack increases, the vortex breakdown points tend to move toward the apex of the wings. Under dynamic condition,hysteresis behavior can be found for the vortex breakdown position which is also asymmetrical on the left and the right sides at zero sideslip angle. As the model is adjusted with a sideslip angle, the breakdown of the windward vortices occurs earlier, leading to sharp change in the roll moment coefficient. The hysteretic behavior of vortex breakdown becomes more obvious as the reduced frequency increases. The dynamometric test also shows that the hysteresis loops of aerodynamic coefficients are formed under dynamic conditions, which match the hysteresis behavior in the vortex breakdown position observations. Contrary to the pitch-down process, the maximum normal force coefficient and the stalling angle increase with the reduced frequency for the model. The higher reduced frequency results in more circular hysteresis loops.