The invention relates to a double-click detection method of a projection interaction system. The method comprises the following steps of collecting each frame of infrared image generated through finger touch or light pen clicking on a white board in real time to obtain an area change curve, an x coordinate change curve and a y coordinate change curve; judging whether the center point coordinate of a connected domain at each moment is stable enough or not; if so, judging whether the shape of the area change curve is the single-peak shape or the double-peak shape; performing connected domain shape comparison on double peaks and single peaks meeting the conditions; judging whether the shapes are similar or not; if so, comparing the gravity center positions and the superposition degree of twice single-click actions at the former moment and the later moment; and if the gravity center position difference is small, and the superposition degree is high, judging the action to be the double-click action. The double-click detection method has the advantages that the twice touch or clicking actions in the double-click process are analyzed in aspects of the area change of the connected domain, the stability of the center coordinate, the touch duration, the touch interval time, the shape of the touch region, the superposition degree of the touch region and the like; and the stability is improved.