(Objective)(Method)Compare of the growth, the ratio of RNA/DNA,digestive enzyme and related immune enzyme activities in normal growth seahorse(8.57±0.61cm,1.51±0.38g) and slow growth seahorse(6.68±0.35cm, 0.81±0.14g)of Hippocampus erectus were studied at 110d raising, respectively. (Result)The results showed that the average daily gain, rate specific growth, condition factor and viscera index in the normal growth seahorse were significantly higher than that of the slow growth seahorse(P<0.05) , respectively.The normal growth seahorse grew more faster than that of the slow growth seahorse when the body length was 5.026cm. The amylase ,protease and lipase activity in normal growth seahorse were as the same tendency as that of the slow growth seahorse under different reaction temperatures (5 ℃, 15 ℃, 25 ℃, 30 ℃, 35 ℃, 45 ℃ and 55 ℃)and pH (2.0、3.0、4.0、5.0、6.0、7.0、8.0 and 9.0), however, the digestive enzyme activity of the former were much higher than that of the latter except amylase activity at 35~55 and protease activity at 5~25. ℃.The activities of ACP、AKP、T-AOC and SOD in normal growth seahorse were more 12.83%、48.21%、44.71%and 65.75% than that of the slow growth seahorse(P<0.05), respectively.The MDA of the normal growth seahorse was only 61.09% of that in the slow growth seahorse(P<0.05),and the ratio of RNA/DNA in the normal growth seahorse was higher 23.75% than that of the slow growth seahorse(P<0.05). (Conclusion) There were significantly different between in two growth status seahorse in growth, digestive enzyme and related immune enzyme activities.