Biodiesel is primarily fatty acid methyl esters (FAMEs), usually obtained by reaction of oils with methanol. Conventional commercial methods used to convert oils to biodiesel were based on the esterification/transesterification reactions with participation of acid/base catalysts. In this study, a new developed method, subcritical methanol method (SMM) without adding catalysts was employed for direct-synthesis of biodiesel from wet Chlorella sp biomass. The effects of reaction parameters on FAME conversion such as reaction temperature (165-185°C), ratio of methanol to biomass (10/1-25/1 g/g), water content (5-80 wt%) and reaction time (1-12 h) were studied. Experiment results showed that, FAME conversion increased with increase of reaction time and highest FAME conversion of 95% was obtained at 175°C, 12 h reaction, 20/1 (g/g) of methanol to biomass and 50 wt% of water content. It can be concluded that a reasonable FAME yield can be achieved from the direct conversion of wet algae biomass under the subcritical condition of methanol. This is one of the most important advantages of the subcritical method over the conventional method in biodiesel production.