The invention discloses a multi-source information fusion-based single-target position determining method and system. The method includes the following steps that: the alternative target positions ata current time point and alternative target positions at a previous time point of infrared images, television images and laser spot images acquired by a plurality of sensors are determined; distancesbetween the alternative target positions at the current time point and distances between the alternative target positions at the previous time point are calculated, and are compared with a first set distance threshold, and whether a first comparison result and a second comparison result satisfy an information fusion constraint condition is judged, if the first comparison result and the second comparison result satisfy the information fusion constraint condition, a target position at the previous time point and a target position at the current time point are determined, if a distance between the two target positions is greater than a second set distance threshold, the target position at the current time point is determined as a single-target position, if the distance between the two targetpositions is not greater than the second set distance threshold, images at a next time point which are acquired by the plurality of sensors are obtained until a single-target position is determined. With the method or system provided by the invention adopted, the timeliness, accuracy and automation level of single-target position determination in a complex environment can be improved.