Structured illumination microscopy (SIM) is suitable for biological samples because of its relatively low-peak illumination intensity requirement and high imaging speed. The system resolution is affected by two typical detection modes: Point detection and area detection. However, a systematic analysis of the imaging performance of the different detection modes of the system has rarely been conducted. In this study, we compared laser point scanning point detection (PS-PD) and point scanning area detection (PS-AD) imaging in nonconfocal microscopy through theoretical analysis and simulated imaging. The results revealed that the imaging resolutions of PS-PD and PS-AD depend on excitation and emission point spread functions (PSFs), respectively. Especially, we combined the second harmonic generation (SHG) of point detection (P-SHG) and area detection (A-SHG) with SIM to realize a nonlinear SIM-imaging technique that improves the imaging resolution. Moreover, we analytically and experimentally compared the nonlinear SIM performance of P-SHG with that of A-SHG.