This paper aims to understand the potential of using wheat straw (WS) as a source for composite. High quality fiber bundles are obtained from wheat straw using a simple alkaline treatment method. Wheat straw fibers (WSFs) are used with PLA fibers to make composites. The effect of sodium hydroxide concentration and temperature of the treatment processes for wheat straw fibers on the tensile and flexural properties of the PLA/WSF composites has been investigated. The contact angle of WSF has also been studied. It shows that the the mechanical properties of PLA/WSF composites are optimal when the sodium hydroxide concentration is 2.5% and the alkali treatment temperature is 125°C. The contact angles after alkali treatment decrease significantly, indicating that the surface wettability of the treated wheat straw is improved.