The monitoring of embryo in the period of egg’s incubation is very important for the development of poultry industries. A monitoring system was devised, which can extract the heartbeat signals of the chick embryos in the period of incubation. A novel semi-invasive method was developed to measure these signals. With this method, it is needed to make a small hole on the top of the egg's air chamber by a pin in order to amplify the heartbeat signals through the egg’s air chamber. And then a piece of thin tinfoil is pasted on the small hole, and the transducer of displacement is employed to measure the vibration of thin tinfoil. So the embryo can be inspected whether alive or not by the signals. Taking advantages of high reliability and simple operation, the system can be used to identify the live bird embryos without affecting the development of embryos. This research can provide a foundation for further exploring the automatic monitoring of the process of embryonic development.