Studies were carried out on the effect of high temperature (20, 23, 25, 27 and 28 ℃) on mucous cells of juvenile turbot (Scophthalmus maximus) by method of ABPAS (AB pH 25, pH 1.0) combined staining. Results showed that significant changes in the distribution, numbers and type of skin mucus cells occurred following high temperature treatment. Compared to the control group (16 ℃ ), the number of typeⅡmucus cells had the maximum increasing, type Ⅳ seconded, typeⅠshowed no significant change, and type Ⅲ presented no regularity change. The skin mucus comprising a number of hydrolase such as lysozyme, acid phosphatase, alkaline phosphatase and so on, which create an acidic environment to protect the fish from damage. With the temperature increasing, pathogenic microorganisms become more active and have a greater threat to the health of the fish. In order to prevent pathogen invasion, the acidic mucus has a significant increased at high temperature. TypeⅡand Ⅳ mucus cells were ABpositive and containing acidic mucoitin, and the increase in the number may create mucus for the skin to defend pathogenic intrusion.