Preparation and properties of wood/plastic composite (WPC) with high content of wood filler around 80% are reported focusing at: effects of high filler content, preparation of all bio-based composite by using poly(lactic acid) (PLA) as plastic material and cellulose esters as compatibilizer, and method for improving weather resistance of wood/PP composite. Addition of about 2% of cellulose esters of C4-C6 aliphatic carboxylic acids was effective for improving the bending strength of high wood content WPC of PLA by slowing down the crystallization rate of plastic. For improving weather resistance of wood/PP composite, top-coating was found most effective.