Rhodamine B(RhB) functionalized Bismuth Ferrite Oxide(BFO)/Titanium dioxide(TiO2)/Silver disulfide(AgS)nanoparticles were used to build a fluorescent turn-off sensor for the detection of Chlorpyrifos(CLP). The fluorescence was drastically quenched by the RhB fluorescence resonance energy transfer to the surface of BFO/TiO2/AgS NCs via electrostatic interactions. Then the addition of CLP to RhB@BFO/TiO2/AgSNCs initiates the loss of fluorescence by the adsorption of CLP molecules to the turn-off sensor probe. Under favorable conditions, the linearity between the fluorescence quenching and the concentrations was monitored and the limit of detection was estimated to be 0.006 ppm, 0.004 ppm for 2:1 and 3:1 ratio, with the fluorescence quenching efficiency ranges from 92.9 to 94 %.