Marine fishing industry is the main field of energy consumption and carbon dioxide emission.Fishing vessels are with low level and have large potential of energy saving.This paper summaried the present status of the fishing vessels energy consumption and emissions in China, analyzed the characteristics of the biodiesel and the advantages and disadvantages as an alternative fuel, proposed the improving measures to blend biodiesel in diesel engines according to the features of marine fishing vessels. It performed a cost benefit analysis for the energy saving effect of blending 5% biodiesel in fishing boat energy.The results showed that there would be an average reduction about 1 371 yuan in fuel costs and 2 000 yuan in maintenance costs per year per ship if blending 5% biodiesel in marine fishing vessels,but an expensive cost of renovation. If all of Chinese diesel marine fishing vessels were blended 5% biodiesel, there would be a reduction of carbon dioxide emissions each year nearly 134 000 tons,thus it would produce more than 4 million yuan of social environmental benefits each year according to the current international carbon trading price.Biodiesel has certain economic advantages and significant environmental performance that can promote energy conservation of Chine’s marine fishing vessels and implementation of national emission reduction targets.