A camera in-line calibration method based on a line model was proposed. By automatically tracking the edge of an object, the internal and external parameters of the camera were solved linearly while the corresponding relationship between object edge and image edge was established. On the basis of the relationship and the initial values of internal and external parameters, the camera parameters were estimated optimally by developing a new error model between the model line and image line with the endpoint information. The simulation and experiment were performed. The internal and external parameters of the camera were calibrated by proposed method and traditional checkerboard interior angle method, and the calibration results were compared. The results only by using edge information show that the proposed method have the almost the same accuracy with the traditional method and the reprojection error(RMS) is 0.6 pixel. In conclusion, the proposed calibration method can implement the estimation of internal and external parameters only by using the object with a standard size and can obtain the same calibration precision as that of traditional method without preparation of the plane calibration object. It is more flexible and practical.