Abstract: Differential expression of myrosinase genes CpTGG1 and CpTGG2 in different organs of Carica papaya was investigated by RT-PCR, The results indicated that CpTGG1 was expressed in stem, leaf, flower and seed, not expressed in root, while CpTGG2 was only expressed in root, and no expression was found in other organs, which indicated that two myrosinase genes have functional allocation. Myrosinase activity was detected in all the tested organs except for pulp, which is consistent with the result of RT-PCR. Myrosinase isolated from leaf tissue had an optimal reaction pH of 8.0, an optimal temperature of 45℃, and optimal Vc concentration of 1.5mM. Papaya myrosinase was inactivated by high temperature and inhibited by high concentration of salt, which is different characteristic compared to other reported myrosinases.