Abstract: Objective To identify circulating tumor cells by single-cell cDNA amplification techniques． Methods Individual tumor cells from blood cells were separated by immunofluorescence staining, and then the cells were lysed and total RNA was protected by the lysate． First strand cDNA was transcripted using modified primer P1(dT)₂₄and then tailed with poly dA． Second-strand cDNA was synthesized using modified primer P2(dT)₂₄． Then the double-strand cDNA was amplificated using primer P1(dT)₂₄and P2(dT)₂₄．At last, the amplificated cDNA was used to detect cell specific marker of CD45, EpCAM and CK19 by PCR． Results Our results showed that the high-quality full-length cDNA was produced by the single-cell cDNA amplification techniques which could improve the effect of PCR significantly． The expression of CD45, EpCAM and CK19 detected by cDNA amplification techniques combined with gene specific PCR could identify tumor cells from blood cells effectively． Conclusion Single-cell cDNA amplification techniques can identify tumor cells from blood cells．