To overcome the traditional image ranging algorithm dependent on camera attitude and parallax, an attitude angle estimation-based ranging method of tank target, in monocular image cathched by observe control and launch system charge coupled device, is proposed. Firstly, multistage scale invariant feature transform matching method is applied to obtain the template with minor error comparing with current target by fast attitude angle estimation. Secondly, the template and current target are used to form a novel monocular range model, without camera attitude and parallax between two images. In such a model, the features points matching the tank target image of the template are projected to the approximated 2D world coordinate with the assumption of far distance and tiny error of the attitude. Thus we set up the mapping relationship between the image points and target points, and then external parameters of camera are achieved by monocular camera calibration to calculate the distance of the camera center from target center. Series of targets range from 200 m to 2 500 m are adopted to verify the effectiveness of the proposed algorithm. Sequentially, the alteration of error along with distance increasing is analyzed, and the comparison between measurement error and the maximal tolerance of middle-to-terminal guidance under various ranges is executed. The results indicates that the proposed algorithm do not need to capture the accurate position and angle of camera, resulting in fast and far distance measurement of individual anti-tank missile system in field. Meanwhile, the maximal relative error is 4.9% and the maximal absolute error is 87.7 m, which satisfy the demand of the biggest tolerance errors in the whole range of missile.