Abstract: In response to needs of development of fine agricultural production management and intelligent agricultural equipment，a grain flow sensor device was developed based on impulse theorem and piezoelectric sensor detection technology.A yield monitor system based on CAN bus for impulse grain flow combine harvester was developed by using CAN bus technology.Through test and data analysis，impulse grain flow sensor static detection accuracy was stable，accurate，with fast dynamic measurement and accurate.Designed grain flow yield monitor system had advantages of real-time performance，small measurement error and stable transmission combined with characteristics of CAN bus，such as stable operation and strong real-time performance，grain measurement error within 8%，grain flow monitoring was timely and accurate，grain yield prescription chart drawn from grain flow was credible and practical.