In order to improve imaging quality of the single compressive sensing ghost imaging and reduce the internal and external interference, the intensity spread function analysis of single compressive sensing ghost imaging was proposed. The imaging process was analyzed based on the principle of single compressive sensing ghost imaging. It is found that Fresnel diffraction and atmospheric turbulence are main causes which result in poor imaging quality. Aiming at these two factors, the formulas of intensity spread function were derived, and the influence of focal length to aperture lens ratio and source wavelength on ghost imaging were studied. Simulation results of single compressive sensing ghost imaging indicate that the effects of diffraction can be restrained by using the projection lens with the ratio of focal length and aperture in the range of 2~5. Besides, the short wavelength is suitable for imaging under the weak atmospheric turbulence. By contrast, the long wavelength is a better choice for imaging under strong atmospheric turbulence. The experiment verifies the conclusions of simulation. Therefore, the proposed method is effective to improve imaging quality and optimize the imaging system.