Because of the potential joint effects of metal oxide nanoparticles (NPs) and their coexisting chemicals in the environment,the ecological risk of NPs should consider the impact of the coexisting chemicals.Despite of the abundant studies on NP toxicity,there have been few studies concerning the mixture toxicity of nanoparticles and their coexisting chemicals.This paper focused on the mixture toxicity of NPs and their coexisting chemicals represented by humic substance and surfactant.The obtained results based on the bioluminescence inhibition on Photobacterium phosphoreum indicated that the single toxicity of NPs may be influenced by the compositions and the valent,but the particle size or the surface charge.Among all the NPs,ZnO had the exceptional antagonism joint effects with other NPs and sodium humate on behalf of the humic substance,which probably resulting from the dissolved Zn ions from ZnO NPs.In addition,cationic surfactant dodecyl trimethyl ammonium chloride on behalf of the surfactant,also exhibited different joint effects on the nanoparticles toxicity through changing hydrodynamic diameters and surface charge of nanoparticles.