A novel method was developed for the determination of seven triazine herbicides in environmental water samples by magnetic solid-phase extraction with graphene-based magnetic nanoparticles (G-Fe3O4 MNPs) as the adsorbent coupled with gas chromatography-mass spectrometry detection. The main factors influencing the extraction efficiency including the amount of G-Fe3O4, the extraction time, the pH and the ionic strength of sample solution and the desorption conditions were optimized. Under the optimized experimental conditions, the enrichment factors of the method for the analytes were in the range from 574 to 968; the linearities of the method ranged from 0.01 to 10.0 microg/L for simazine, propazine, metribuzin, simetryn and cyanazine, from 0.05 to 10.0 microg/L for atrazine and from 0.01 to 8.0 microg/L for prometryn, with the correlation coefficients (r) ranging from 0.996 8 to 0.999 8. The limits of detection were in the range between 1.0 and 5.0 ng/L. Good reproducibilities were obtained with the relative standard deviations below 10.5%. The developed method was applied to the analysis of the triazine herbicides in different water samples (lake, well and tap). The recoveries of the method were in the range from 79.8% to 118.3% at the spiked levels of 0.5 microg/L and 2.0 microg/L. The results indicated that the developed method can be used as a simple and efficient technique for the determination of the triazine herbicides in environmental water samples.