The present invention relates to a scalable multiplex PCR method that can simultaneously amplify overlapping amplicons without the drawbacks of conventional multiplex PCR. The method selectively amplifying target nucleic acid fragments having an overlapping region. The method comprises the steps of: obtaining a first nucleic acid sequence comprising a first tag t2 and a first forward primer F1, obtaining a second nucleic acid sequence comprising a second tag t1 and a first reverse primer R1, obtaining a third nucleic acid sequence comprising the second tag t1 and a second forward primer F2, obtaining a fourth nucleic acid sequence comprising a third tag t3 and a second reverse primer R2, wherein each primer is a gene-specific primer; performing initial cycles of PCR; and then performing later cycles of PCR at higher annealing temperatures to obtain amplification products.