In order to realize the monitoring and analysis of communication instructions between User Application(UA)and Cockpit Display System(CDS) in ARINC661 cockpit display system, we studied the instruction filtering technology. An analysis was made to interactive instructions in the communication process, and the structure of the binary tree was used to obtain a filtering algorithm, which is efficient for data filtering. Ground tests showed that the filtering method is correct, and the designed instruction monitoring and display software is reliable and has good performance, which plays a very important role in the development of cockpit display system.