An ultra-sensitive and highly selective parathion methyl(PM) detection method by surface plasmon resonance(SPR) combined with molecularly imprinted films(MIF) was developed. The PM-imprinted film was prepared by thermo initiated polymerization on the bare Au surface of an SPR sensor chip.Template PM molecules were quickly removed by an organic solution of acetonitrile/acetic acid(9:1,v/v), causing a shift of 0.58 in SPR angle. In the concentrations range of 10à13–10à10mol/L, the refractive index showed a gradual increase with higher concentrations of template PM and the changes of SPR angles were linear with the negative logarithm of PM concentrations. In the experiment, the minimum detectable concentration was 10à13mol/L. The selectivity of the thin PM-imprinted film against diuron,tetrachlorvinphose and fenitrothion was examined, but no observable binding was detected. The results in the experiment suggested that the MIF had the advantages of high sensitivity and selectivity. An ultra-sensitive and highly selective parathion methyl (PM) detection method by surface plasmon resonance (SPR) combined with molecularly imprinted films (MIF) was developed. The PM-imprinted films were prepared by thermo-initiated polymerization on the bare Au surface of an SPR sensor chip. Template PM molecules were quickly removed by an organic solution of acetonitrile / acetic acid (9: 1, v / v), causing a shift of 0.58 in SPR angle. In the concentration range of 10à13-10à10 mol / L, the refractive index showed a gradual increase with higher concentrations of template PM and the changes of SPR angles were linear with the negative logarithm of PM concentrations. In the experiment, the minimum detectable concentration was 10 13 mol / L. The selectivity of the thin PM- imprinted film against diuron, tetrachlorvinphose and fenitrothion was examined, but no observable binding was detected. The results in the experiment suggested that the MIF had the advantages of high sensitivity and selectivity.