An on-line system which based on acoustic resonance employed digital signal processer (DSP) as its core device for eggshell crack detection. The system consists of the IR trigger for detecting the egg’s coming, the motor drive for driving the DC motor, the signal conditioning circuit for signal amplification and filter and DSP for control and signal processing. Based on the analysis of response signal of eggshell which excited with a light mechanical, four featured descriptors were exacted for discriminating intact and cracked eggs. By using the on-line system for detection of cracked eggs, the identification rates of intact eggs and cracked eggs were 93.75% and 96.25%, respectively. This system can detect 5 eggs within one second, it completely meet the needs of on-line detection.