1. A visual tracking system, for generating a tracking result signal of a target, allowing an active moving platform to move according to the tracking result signal, and thereby positioning the target at an image center, the visual tracking system comprising: a sensor unit for capturing images of a monitored scene consecutively; an image processor unit, coupled to the sensor unit, for detecting whether a target is entering the image, extracting characteristics from the image to formulate at least two models of the target, and calculating a matching score of the models; a hybrid tracking algorithm unit, coupled to the image processor unit, for using a fuzzy theory to create a membership function for the matching score of the models, and using the membership function for the fuzzy computation to determine the levels of excellent, above average, average, below average or poor, and performing a defuzzification for the fuzzy computation to obtain the final matching scores, and computing the probability of the target position for each pixel in the monitored scene to produce an optimal matching result; and a visual probability data association filter, coupled to the hybrid tracking algorithm unit, for receiving the optimal matching results to remove an interference of tracking from a complicated background and output the a tracking result signal, wherein the membership function is a triangular membership function (trimf), and the fuzziness degrees are referred to as excellent, above average, average, below average, and poor, respectively.