The present invention relates to the field of parts of a sunshade umbrella, in particular to a controllable automatic umbrella unfolding device, which comprises an upper runner, a middle runner, a lower runner and a center bar. The upper runner of the umbrella is fixed at the top end of the center bar, the middle runner and the lower runner of the umbrella are movably sleeved on the center bar, the upper runner is connected with long ribs, the long ribs are connected with short ribs, the middle runner is connected with branch ribs, the branch ribs are connected with the short ribs, the short ribs are connected with the lower runner, a gas spring is disposed in the center bar, the tail end of a cylinder barrel of the gas spring is connected with the middle runner of the umbrella, a valve is arranged at the end of a piston rod of the gas spring, and a valve opening device is disposed corresponding to the valve. The automatic umbrella unfolding device has the beneficial effects of: automatic umbrella unfolding, controllable stroke, simple structure, very few components and relatively low cost.