An on-line system based on acoustic resonance combined digital signal processing (DSP) system was developed for eggshell crack detection. It was achieved by analysis of measured frequency response of eggshell excited with a light mechanical force. Based on previous experiments, differences between the signals of intact eggs and cracked eggs were analyzed. Five excitation resonant frequency characteristics of eggs were used as input vectors of identification model to discriminate intact and crack eggs. The identification results were transmitted to host computer. The system was employed for on-line detection of cracked eggs, identification rates of intact eggs and cracked eggs were 92.0% and 90.5%, respectively. This system can detect 5 eggs within one second. It completely meets the need of on-line detection. 