The pristine nanosheet, nano cone and nanotube structures with equal number of Zn and Se atoms were constructed in order to study the effect of adsorption of NO2 at Zn and Se sites of the nano structures. The pristine ZnSe and NO2 adsorbed ZnSe nanostructures were optimized using density functional theory implemented in Gaussian09 pacakage. The B3LYP hybrid exchange correlation with LANL2DZ as basis set was used in this study to exploit the nano structures. Structural and electronic properties of such as HOMO-LUMO, band gap and mulliken population of ZnSe nano structures were studied and reported. Density of States(DOS) spectra of pristine and NO2 adsorbed ZnSe Nano sheet, cone and tube structures show that nano cone and nanotube structures have a higher number of quasi bound states on both valance and conduction band sides compared to the nano sheet structures. To study the adsorption effect of NO2 on Zn and Se sites of various ZnSe nanostructures, the adsorption energy was calculated and discussed.The ionization potential and electron affinity and the reactivity descriptors of ZnSe nanostructures such as chemical hardness(), chemical potential (μ), softness(S) and electronegativity(χ) were calculated for pristine, NO2 adsorption at Zn site and NO2 adsorption at Se site for ZnSe nano structures and reported.