Abstract: Using the cloth of glass fiber and nonwovens of polyphenylene sulfide (PPS) as reinforcement and matrix, the glass fiber cloth/PPS nonwoven composite boards were prepared by hot pressing which were put in the oven for heat treatment. The mechanical properties, crystallinity, type and size of grain and micro morphology of glass fiber cloth/PPS nonwoven composite boards were tested and characterized by Instron, XRD, polarizing microscope(PLM) and SEM. The results show that the bending strength, flexural modulus and notched impact strength of the composite board are obviously improved with the increase of the temperature and time of heat treatment. When the temperature of heat treatment is 220℃ and the time of heat treatment is 2 h, the mechanical properties of the composite board are the best. The bending strength, flexural modulus and notched impact strength are 285.7 MPa, 7.8 GPa and 85.0 MPa, respectively, increased by 63.2%, 469.0% and 37.8%, compared with those without heat treatment. The micro morphologies of the glass fiber cloth/PPS nonwoven composite boards show that the interfacial adhesion has been greatly improved.