Abstract: According to the first principles, the lattice structure, elasticity and electronic properties of three kinds of chromites spinel subject to slight structural variation are studied by the pseudowaves plane (PWP) approach based on density functional theory (DFT) and generalized gradient approximation (GGA). The calculated and experimental results are compared and show that the values of lattice constant, bulk module and shear module are all in good agreement. The slight structural variation enables the bulk modulus to decrease considerably and the Young's modulus increases clearly with increasing coordinate value of atomic oxygen, but the shear modulus and Poisson ratio decreases substantially. It is concluded that the electron exchange action between iron and chromium actions is the main influencing factor on the variation of the elasticity after analyzing the electronic properties such as DOS (density of states), the most nearest-neighboring bond lengths between Fe/Cr actions and O anion and electronic populations.