Abstract: The maleic anhydride-α-olefin copolymers and their esters were prepared from maleic anhydride, α-C_12-18 olefins and C_12-18 alcohols by binary polymerization and alcoholysis.The copolymers and their esters were employed as pour point depressant to improve the low-temperature fluidity of biodiesel. The effects of prepared pour point depressants on the pour point of palm oil biodiesel, before and after diluted by anhydrous ethanol and O^# diesel, were evaluated. In addition, the pour point depression effects of prepared pour point depressants were verified when applied to reduce the pour point of soybean oil biodiesel. The results indicated that: when the mass fraction of anhydrous ethanol and O^# diesel in palm oil biodiesel was 40% and 80%, adding 3% prepared pour point depressants, the pour point reduced by 8℃and 25℃, respectively;by adding of 0.5% prepared pour point depressants into soybean oil biodiesel, the pour point reduced by 15℃.

Key words: biodiesel, pour point depressant, pour point, low-temperature fluidity