The effect of frozen treatment temperature(-80 ℃ and -20 ℃) on quality of Penaeus vannamei was investigated by analyzing of biochemistry, freshness and color characters of prawn samples. The frozen treatment induced the increase of thawing loss, TVB-N and L*, decrease of freshness. The pH of prawn decreased in the first few days and then increased rapidly. The frozen temperature showed different influence on prawn storage character, especially on thawing loss and freshness index after being storage for 6 days. Frozen treatment at -80 ℃ may effectively reduce the thawing loss and thus keep freshness of the prawn. After a -80 ℃ frozen treatment for 20 days, analysis of pH, TVB-N and L* shown that -80 ℃ frozen treatment could alleviate quality changes of prawns.