In order to optimize the fabrication of SiO2 tubes immobilized with antibody for hepatitis C virus antigen (HCAg) detection, we formed the activated amino on the surface of SiO2 tubes by using the activation of aminosilane. Then we immobilized the hepatitis C virus (HCV) monoclonal antibody on the surface of SiO2 tubes by using glutaraldehyde as a chemical cross-linker, followed by detecting HCAg. Sequence tests showed that when the SiO2 tubes were treated in 10% (V/V) aminosilane solution and 3% (V/V) glutaraldehyde solution for 3 hours and 2 hours, respectively, the HCV monoclonal antibody had high immobilization efficiency and low nonspecificity, and the HCAg was detected to 1 ng/mL. This experiment can provide principle and experimental data for establishment of HCAg magnetic immunoassay system.