A highly selective method for the analysis of triazine herbicides in corn samples based on molecularly imprinted solid phase extraction (MISPE) has been developed. Molecularly imprinted polymers (MIPs) were synthesized by precipitation polymerization using atrazine as a template, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a crosslinker, and 2,2′-azobis-isobutrynitrile as an initiator. MISPE was developed for the on-line and automated enrichment of atrazine, simazine, terbutryn, simetryn and ametryn from corn sample extracts. High-performance liquid chromatography and time-of-flight mass spectrometry were used for the separation and confident determination of the herbicides. The limits of detection and quantitation of the proposed method were set to be 1.6–3.3 μg kg−1 and 5.0–10.0 μg kg−1. The method was successfully applied for the analysis of five types of corns and the recoveries of the triazines from the spiked samples ranged from 80.2 to 119.1%.