1. A hand positioning method used in a human-computer interaction system comprises: a step of continuously capturing a current image of a monitored display area so as to obtain a sequence of video images including a foreground object; a step of extracting a foreground image from each of the captured video images, and then carrying out binary processing with regard to the extracted foreground image so as to obtain a binary foreground image; a step of obtaining a set of vertexes of a minimum convex hull of the binary foreground image, and then creating areas of concern serving as candidate hand areas by letting the respective vertexes of the minimum convex hull of the binary foreground image be the central points of the areas of concern; and a step of extracting hand imaging features from the respective created areas of concern, and then determining a hand area from the candidate hand areas by carrying out pattern recognition based on the extracted hand imaging features.