Arsenic (As) has been observed to co-exist with atrazine (ATR) in soils worldwide. ATR, as an organic chemical, may affect the availability of As and further influence its uptake by organisms. Here we used a novel passive sampling technique, DGT (diffusive gradients in thin-films), to compare with other two conventional sampling approaches (soil solution extraction and ‘Olsen As’ measurement) to investigate the influence of ATR addition (normal recommended level and contaminated level) on the availability of As in soils, to further interpret the potential risk of As in soil environment. The effect of adding ATR on the behaviour of As in soils was limited. When the concentration of ATR was much higher, the availability of As in soils was supressed, the labile pool size was also affected, but the R value did not change much. The properties of the soils also played an important role by affecting the states of the compounds.