A new idea of improving complementary metal-oxidesemiconductor (CMOS) thermopile performance is introduced to increase the absorption of infrared radiation by leading the photonic crystal (PC) into thermopile in this paper. A highly sensitive infrared detector requires an excellent signal induced by incident IR radiation to maximize the temperature change. A photonic crystal structure offers significantly effect for absorption of infrared radiation. Firstly we develop such a structure of thermopile with high performance by using 0.35μm 2P4M CMOS IC compatible process which can be easily and exactly fabricated. Several designs of infrared microsensors are proposed to study influential parameters from photonic crystal structure. The measurement results show these devices get greatly responses higher than the thermopile without photonic crystal. To that end, an optimal parameter is acquired at the same time. Our design is proved to be adequate for commercial batch production.