The invention provides a method for preparing a synthetic peptide antigen 2600 of a swine O-type foot and mouth disease through a solid-phase fragment process. The method comprises the steps of with resin as a raw material, sequentially connecting 9-fluorenylmethoxycarbonyl protective amino acid to prepare a protected peptide fragment, meanwhile, sequentially removing a 9-fluorenylmethoxycarbonyl protecting group, carrying out linker reaction by using a condensing agent, and cutting off the protected peptide fragment by using dilute acid or weak acid; connecting the fragment and 4-(4'-dimethoxy-9-fluorenylmethoxyaminomethyl)-phenyloxymethyl resin step by step, and then, connecting the fragment and a T helper cell epitope; removing the protecting group and the resin by using concentrated acid or strong acid to obtain a crude peptide of the synthetic peptide antigen 2600; and purifying by using ion exchange resin and a tangential flow film packaging system, and removing small molecules and salt through a concentration system to obtain the synthetic peptide antigen 2600. The method provided by the invention has the characteristics of stable process, short production period, convenience in obtaining raw and auxiliary materials, few wastewater, waste gas and waste residues, low production cost, high yield and the like.