Heterodyne efficiency is reduced by aberration of receiving antenna for space coherent optical communication. On the assumption that local oscillator wave is Gaussian distribution and signal wave is Airy distribution, a simple analytic expression of heterodyne efficiency is given for an aberration-free system. When the ratio of signal Airy disk radius to local oscillator Gaussian 1/e field radius at focal plane is 1.71, maximum heterodyne efficiency of 81.45% can be obtained. The effect of signal wave receiving antenna’s tilt, defocus, spherical, coma and astigmatism aberration on heterodyne efficiency is analyzed by assuming that local oscillator wave is perfect Gaussian distribution. One-dimensional integral expression of heterodyne efficiency including aberration effects is given. The result shows that one wavelength spherical aberration could induce 0.9 dB heterodyne efficiency loss even by using defocus adjustment. So spherical aberration should be carefully considered in designing an on-axis receiving antenna.