In-situ integrated microlens could concentrate the illuminated infrared light without changing the packaging structure.By fabricating in-situ integrated microlens on the illumination side of the Inferred Focal Plane Array (IRFPA),signal is increased,and the crosstalk is suppressed,which has a significant meaning to improve the performance of the small pixel(10 μm) HgCdTe IRFPA.Microlens for the small pixel (10 μm) has been carefully designed and successfully fabricated in the paper.The signal bas been effectively increased,and the noise equivalent temperature difference (NETD)has been decreased.