Abstract: The absolute orientation of aerial imagery over urban areas combined with vertical lines is discussed.According to the theory of vanishing point,the relationship between the spatial vertical lines and azimuth angles of the aerial imagery,and the corresponding error equation of the vertical lines have been deduced.Then the necessary control points number of the single photo space resection and absolute orientation of the single stereo-model has also been anlysised.The test results show that,while the vertical line constrains has been applied in the single photo space resection and single stereo-model absolute orientation,not only the accuracy of the absolute orientation is the same as the traditional absolute orientation with control points only,but also the necessary control points number and the dependency of the layout of the control points have been reduced.The work presented provides a new way for the calculation of the exterior orientation parameters of the aerial imagery over urban areas.