Abstract: 1. 5 wt% carbon fiber(C_f) reinforced polymethyl methacrylate-polymethyl acrylate ( PMMA-PMA)matrix composites were prepared by the suspension polymerization process with initiation reaction using methyl methacrylate (MMA) and methyl acrylate (MA) as raw materials, and potassium persulfate(KPS) as initiator.The effects on flexural strength and bioactivity of the prepared composites fatigue behavior were particularly investigated. The flexural strength, microstructures and phase composition of the composites were characterized by the universal testing machine, X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses, respectively. The results show that the composites flexural strength displays no clear change and there are no cracks on the stress surface of the composites within 0～5000 cycles. The deposition of the hydroxyapatite particles increases with extending soaping time of C_f/PMMA-PMA composites dipping in simulated body fluid (SBF) solution, which shows that the prepared composites have good bioactivity. In addition, there is almost no influence on the mechanical performance of the composites when they are soaped in SBF solution.