The invention discloses a preparation method of a recombinant anti-TNF-alpha completely humanized monoclonal antibody. The method comprises: synthesizing a nucleic acid sequence of a recombinant anti-TNF-alpha completely humanized monoclonal antibody, using the obtained nucleic acid sequence of the recombinant anti-TNF-alpha completely humanized monoclonal antibody to construct a carrier, transfecting a host cell, and screening high-expression cell clone to establish a cell bank; and using the obtained cell strain for culture, and performing separation and purification to obtain the recombinant anti-TNF-alpha completely humanized monoclonal antibody. Light chains and heavy chains of the recombinant anti-TNF-alpha completely humanized monoclonal antibody is designed and synthesized according to preferred codons of Chinese hamsters, an eukaryotic expression carrier is established, a host cell CHO-GS- is transfected, serum-free culture is adopted, and separation and purification are adopted to obtain the high-purity recombinant anti-TNF-alpha completely humanized monoclonal antibody. The preparation method is simple to operate, short in production period, and suitable for industrial production.