Abstract: The capacity for carbon fixation of G.Lemaneiformis was estimated based on the cultivation experiments and field investigation in Shen'ao bay, in spring 2014.At the same time, we analyzed how its carbon fixation ability is affected by environmental factors.The results show that the total carbon fixed by G.Lemaneiformisis about 613.9 t in spring.The seawater temperature ranged from 13.94℃ to 22.97℃ during the experiment.The growth rate of G.Lemaneiformis ranged from 2.44%/d to 6.40%/d.The temperature and light affected the light-harvesting pigment and thus affected the growth rate and photosynthesis of G.Lemaneiformis.This is the key factor that affects the rate of carbon fixation by G.Lemaneiformis.Low nutrient supply inhibits the growth rate, and thus limit the carbon fixation of G.Lemaneiformis.Changing the way of cultivation plus artificial fertilization can effectively promote output, and increase the amount of carbon fixation.