Abstract The defocusing effect of computational ghost imaging (CGI) through atmospheric turbulence is investigated, and the incoherent Lorentz source is proposed to suppress the defocusing effect. The imaging formula is derived to describe the defocusing effect of CGI in the atmosphere, and the comprehensive effects of atmospheric turbulence and defocusing on the imaging resolution of CGI with an incoherent Lorentz source are studied, respectively. It is found that the imaging quality of CGI und