The labeled compounds, CdTe was combined with anti-fluoranthene antibody, had good dispersion and stability with the fluorescence intensity enhancing. A direct competitive fluorescent immunoassay with CdTe-anti-fluoranthene antibody to detect fluoranthene in water sample in the environment was developed. The result showed that fluoranthene can be determined in the concentration range from 0.1 μg/L to 1000 μg/L with a correlation coefficient of 0.9983, a sensitivity of (IC_(50)) of 12.4 μg/L and a detection limit (IC_(20)) of 13.1 ng/L. Trace environmental pollutant in environmental water samples were successfully determined with a good accuracy and suitability. The recovery was between 95.1% and 111.0%, with relative standard deviation less than 9%.