Image rotation is one important aspect on influence and confinement of image quality. The image mirror non-synchronous rotation with scanning mirror will cause image rotation in the focal plane. Consequently, it will lead to the loss of ground information and the image resolution will decrease significantly. In order to improve the dynamic state resolution of aerial remote sensor, it is indispensable to analyze the image rotation of aerial remote sensor. According to the optical reflection vector theory, imaging characteristics of aerial remote sensor with three-mirror reflective optical system are studied. At first, a simple mathematic model is abstracted from the aerial remote sensor. In the Cartesian coordinate system, it can analyze the influence on image quality which is caused by scanning mirror rotation along the direction of position angle and plunge angle by the mathematic method of coordinate transformation. Scanning mirror rotations along directions of plunge and position angles produce image rotation and image motion, respectively. It will provide a theoretical basis for designing a mechanical structure to compensate for drift angle and for the control of integration time of time delayed and integration (TDI) CCD according to the analysis. Test results show that the rotation synchronous error is less than one-third of pixel size and that prime images can be acquired without any blurring. Thereby, the modulation transfer function (MTF) of optical system can be improved.