A detector array target of laser distant-field detect system is designed, and two key factors are analyzed. To determine the size of the array target, the laser diffract effect and the influence of atmospheric turbulence are discussed, three factors that influence the resolution of the array target are analyzed. Three factors are the dimension of laser speckle resulted by atmospheric turbulence, space sampling frequency based on sampling theory and the loss of the frequency spectrum function of the array detector. All of these must be matured in design.