In order to reduce the influence of anisoplanatism on the performance of telescope imaging system, and expand the effective Field-of-view(FOV) of system, anisoplanatic effect in wide-field-of-view telescope imaging system is studied here. First, a numerical simulation of anisoplanatic imaging through volume atmospheric turbulence by using multiple random phase screens has been developed. Then, the mean-square wave front errors of two separate object points between the on-axis position and the off-axis position with angle θ are calculated based on the numerical simulation system under the typical atmospheric condition(atmospheric coherent length r0 = 0.1 m). The results show that when tilt errors have been included in the aberrated wave front, anisoplanatic effect becomes weaker as the diameter D of the imaging system increases, and the ascending variation of the mean-square wave front errors is less severe. Whereas, when tilt errors have been excluded, anisoplanatic effect becomes greater as the D increases, and the ascending variation of these is more severe. The larger the diameter of system aperture is, the weaker tilt anisoplanatism is. For large-aperture telescope imaging system, like D≥5 m, high-order wave front errors are the crucial influence.