The invention belongs to the technology in the field of nucleic acid amplification. An optimized buffer solution specially used for amplifying high GC content fragment is used for the amplification of a DNA template with high GC content and complex secondary structure, and the amplification can not be realized by the general PCR method. The optimized high GC PCR buffer solution system can help the unwinding of the DNA template with high GC content and complex secondary structure, thus enhancing the specificity of primer binding so as to facilitate DNA polyase to extend and pass through a secondary structure area. The buffer solution can be applied to enhance the fidelity of nucleic acid amplification and the amplification of complex templates.