In this paper, the interaction of cucurbit ［8］uril(Q［8］) with thionine (TH) and carbendazim (CBZ) were investigated with fluorescence and UV-Vis spectroscopy. The experimental results showed that the inclusion complex between Q［8］ and TH informed was at molar ratios of 1∶2 in 0.01 mol·L-1 hydrochloric acid solution. The fluorescence intensity of the Q［8］/TH complexes quenched when Q［8］ was added to TH solution, but fluorescence increasing of the Q［8］/TH complex with the addition of CBZ was observed. The fluorescence increasing values show a good linear relationship with the CBZ concentration within 0~3.5 μmol·L-1. The linear regression equation relating fluorescence intensity (If) to CBZ concentration (c) is If=0.45c+32.24 (r=0.999). The detection limit was 9.39×10-8 mol·L-1. Forthemore, the influence of foreign species on the analytical signal of the Q［8］/TH complex in the presence of carbendazim was established. No interference was observed from commonly used foreign species such as metal ions (Fe3+, Mg2+, Ca2+). In particular, benzimidazole compounds thiabendazole and fuberidazole do not interfere with CBZ determination at a specific concentration. The results revealed that complexation of Q［8］ and TH with CBZ offers a fluorescent switching “on-off” effect which will supply a potential application in pesticide residues test.