Taking the mismatch angle between signal and local oscillator beams as an example, we analyze the influence of spatial phase aberration on the heterodyne non-imaging array detector based on theoretical derivation and numerical calculation, and compare the array detector with the single detector with the same size. The research results reveal that the attached phase term of the signal output from detector element will severely affect the performance of the non-imaging array detector. Therefore, when only the spatial phase aberration is concerned, the array detector with a simple linear superposition cannot contribute to the performance improvement of the system. If the attached phase in the signal of detector element is eliminated by a certain method, the non-imaging array detector can increase greatly the signal-to-noise ratio of the heterodyne system even if the aberration is severe. Our results enrich the research of the non-imaging array detector in heterodyne detection and have guiding significance for the application of this technology.