Fluorescence polarization immunoassay (FPIA) is a fast screening technique based on immune competition and fluorescence polarization principle and is most used in the determination of small molecular substance (antigen). FPIA is based on the increase in polarization of the fluorescence of small fluorescent-labeled antigen when bound by specific antibody. FPIA is a homogeneous technique and not affected by solution color and the sensitivity of instrument. No separation step is required for FPIA. Simplifying the assay and minimizing the analysis time are the most notable advantages of FPIA over other immunoassays and FPIA is suitable to screening a large number of samples. The technique has been applied to the determination of pesticides and veterinary drugs in environment and food samples, while no studies have been reported in the correlative field in China. The present paper presents the principle and history of FPIA and its application in the screening determination of pesticides and veterinary drugs.