Objective：To construct a sustained-release system to control the abnormally increase of chromium and cobalt ion concentration persistently and effectively in rats. Methods：First，a sustained-release system loaded with ethylene diamine tetraacetic acid （EDTA） was constructed. Then，the rat models were established by intra-articular injection of CoCrMo nanoparticles. Afterwards，the rat models were randomly divided into 4 groups，injected intraperitoneally with normal saline，EDTA，silica microsphere empty carrier solution and EDTA-loaded system solution，respectively，during which，the rats were injected with CoCrMo nanoparticles as before. The blood chromium and cobalt ion concentrations were measured. Results：After the therapy，the concentration of metal ions in groups receiving EDTA and EDTA-loaded system solution decreased significantly in the short run. However，as the time goes，the concentration of metal ions in group injected with EDTA increased and with EDTA-loaded system solution，stayed low，relatively，there was a statistically significant difference between these 2 groups. Conclusion：This sustained release system can effectively reduce the continuous increase of metal ions in the serum of rats，which can offer an alternative treatment for the abnormally increased metal ion after arthroplasties.