Abstract: In order to investigate the feasibility of biomass resources improving the interface and comprehensive properties of bio-composites, the oxidation modification ammonium lignosulphonate (OMAL) was used to produce the environment friendly OMAL-polylactic acid (PLA)/wood fiber (WF) composites by the high speed mix-flat hot pressing process with WF as matrix and PLA as reinforcement. The influence of OMAL on mechanical and thermal properties of OMAL-PLA/WF composites was investigated. The results show that OMAL can improve the modulus of rupture, elastic modulus and internal bond strength of OMAL-PLA/WF composites with mass ratio 7:3 of WF to PLA, and the optimized mechanical properties are achieved with OMAL dosage of 15wt%-20wt%. When the OMAL dosage is 20wt%, the thermal decomposition initial temperature decreases 45 ℃, the characteristic peak of thermal decomposition rate arises 107 ℃ in advance, the residue quantity increases by 5.3%, the glass transition temperature, cold crystallization temperature and melting temperature shift to low temperature, the storage modulus and loss tangent increase with the temperature range of the platform stage increases about 20 ℃ compared to that of PLA/WF composites.