A cost-effective manufacturing process was proposed to obtain high-performance flax fiber reinforced composites. A short cycle time by direct impregnation method was achieved to meet economic requirement in the automotive industry. Thermal degradation of flax fiber during process time was evaluated to investigate its effect on the impregnation quality. The optimal process conditions such as the process temperature and the mold compression pressure cycle were proposed to achieve the good impregnation quality. The effect of void contents on flexural properties was investigated.