Abstract: The basic principle of egg freshness detection with its optical properties in nondestructive form has been described. The relationship between the transmittance and the freshness evaluation criteria (Haugh Unit, Yolk coeficient and Voaltile salt nitrogen) has been found in the tracing test of the freshness. The freshness index represented by optical properties established could be used as the basis for egg freshness grader design and as the referennce for formulating the stanndard of nondestructive egg evaluation.