Computer Aided Instruction (CAI) is the very important application field of engineering. Computer auxiliary examination management system is the important link of the Computer Aided Instruction, and it is an effective means for teaching evaluation. We found an application of intelligent examination system based on control theory and pattern recognition. It realizes the artificial and automatic control to the hard or easy test questions and the distribution of chapters. It adapts to multi-levels, multi-subjects. A field study validates the effectiveness of the new system.