A method for improving the spatial resolution of an infrared scene projector chip is proposed by making in-plane microstructures. By establishing a simplified two-dimensional heat conduction model, the spatial resolution of the chip with periodical microstructure is calculated. On this basis, the influences of contact area ratio and filling factor of microstructure on the spatial resolution of this infrared scene projector chip are studied and the optimization design of periodical microstructure is realized. The theoretical calculation shows that by fabricating the microstructure with a contact area ratio of 0.18 and a filling factor of 0.52, the spatial resolution can be improved to 10.3 lp·mm ^-1 at an MTF of 0.3, twice that of the chip without microstructure. Two kinds of infrared scene projector chips with different contact area ratios and filling factors are fabricated. The diameter of the chip is 7.62 cm and the thickness is about 800 nm. Using the non-contact steady-state infrared imaging method, the spatial resolutions of these two chips are measured. When the MTF value is 0.3, the spatial resolutions of the chips with contact area ratios of 0.20 and 0.46 are 11.2 lp·mm ^-1 and 6.6 lp·mm ^-1, respectively. Our experimental results coincide well with those of the theoretical calculation, indicating that the proposed method is effective and practical for spatial resolution improvement.