The Surface-Enhanced Raman Scattering (SERS) spectra of the virions of four kinds of insect virus: Nuclear polyhedrosis virus of Trabala Vishnou (TvNPV), Nuclear polyhedrosis virus of Gynaephora ruoergensis (GrNPV), Granulosis Virus of preris rapae (PrGV) and Granulosis Virus of Darna trima (DtGV) adsorbed on the surface of silver colloid particles have been obtained and investigated. The strong interactions appeared between silver surface and COO- groups, NH2 groups or aromatic side-chains in SERS of the molecules of the virions. The intensities of bands related to the vibrations of COO- groups are 458 to approximately 460 cm-1: (upsilon) (COO-), 568 to approximately 577 cm-1: w(COO-), 614 to approximately 624 cm-1: (delta) (COO-), 914 to approximately 934 cm-1: (upsilon) (C-COO-) and the bands related to the vibrations of NH2 groups are 1114 to approximately 1134 cm-1: t(NH2), 1620 to approximately 1632 cm-1: (delta) (NH2), 3390 to approximately 3398 cm-1: (upsilon) (NH2). It indicates that the molecules of the virions adsorbed on silver through both the COO- and NH2 groups. The short-range enhancement results from a chemical interaction between the virion molecules and the silver surface. The bands at low frequency (218 to approximately 236 cm-1) in the SERS spectra of the four samples show that chemiscorption is a main mechanism on silver hydrosis of the virion. The (pi) -electron systems of side-chains of the aromatic amino acids in virion have formed the additional adsorption centers in the molecules of virions, it will decrease the distance between some groups of molecules and the silver surface. So the bands at 928, 914, 930, 934 cm-1, due to the skeletal C-C vibration, have been enhanced.