Abstract: COTS(commercial off-the-shelf) devices are widely used for micro-satellites out of consideration of cost and weight. The total dose effect is one of the main factors restricting their aerospace applications. In order to calculate the total radiation dose for COTS devices more exactly and to avoid over-design, a three-dimentional total dose analysis software is developed based on the Pro/E secondary development technology. The results are compared with the commercial software Space Radiation in the case of a simple model. The comparative results show that our software are valid. The software has been used in the design of satellites in our company. It helps reduce the total dose capability requirement of total dose sensitive devices, and reduce the thickness of shielding.