PCR/SERS assay was constructed based on allele-specific PCR for amplification of common CRC mutant targets including KRAS G12V (c.35G>T), KRAS G13D (c.38G>A) and BRAF V600E (c.1799T>A), followed by SERS nanotags identification of the mutant targets and SERS signal readout of the corresponding mutations. The gene discussed is KRAS; the disease is colorectal carcinoma.