A new class of fluorescent probe produced by conjugating semiconductor quantum dots (QDs) with protein molecule is proposed as an alternative to conventional organic labels. However the fluorescence characteristics of the QD bioconjugates are not clear while they are excitied with one- or two-photon laser pulse. We synthesized specific immunofluorescent probes by linking QDs to alpha fetoprotein (AFP) antibody for specific binding alpha-fetoprotein -an important marker for hepatocellular carcinoma cell lines, and archived specific fluorescence detection with the QDs-Anti-AFP in nude mice. Then, we have analyzed the fluorescence characteristics of QDs-Anti-AFP and original QDs both under one- and two-photon excitations. The results demonstrated that QDs-Anti-AFP's fluorescent spectral and lifetime haven't varied much from that of original QDs. Moreover, QDs-Anti-AFP have exhibited higher fluorescence efficiency than QDs under two-photon examination.