Nonylphenol (NP) was determined using electrochemical method based on ionic liquid-functionalized graphene nanosheet modified electrode. The fabricated electrode was characterized by electrochemical impedance spectroscopy. The different influence parameters, such as pH value, scan rate, accumulation potential, and time, were investigated. Under the optimum conditions, the linear relationship between peak current value and concentration of NP was obtained with differential pulse voltammetry in two ranges from 0.5 to 30 μM and 30 to 200 μM with the detection limit of 0.058 μM (S/N = 3). Moreover, this modified electrode was applied to NP determination in water and soil samples with the recoveries from 94.8 to 104 %, which showed the method could be applied to determine NP in environment. In addition, to explore the damage to DNA, the interaction between NP and DNA was investigated with the association constant (β) of 0.4867 and the Hill coefficient (m) of 3.75 × 105 M−1, respectively.