Based on the requirements of miniaturization, intelligence and low power of CO₂ infrared gas sensor, a special MEMS infrared source chip for CO₂ detection is innovatively proposed with the center temperature of 407℃. The chip is a micro hot plate with X-type suspending bridge structure. And the internal heating area is tungsten heater with ring routing structure, SiO₂ and Si₃N₄ dielectric thin films as the mechanical support film. The infrared source chip is optimized with uniform temperature distribution in heating zone, short thermal response time and low power by the finite element simulation analysis. The chip is fabricated by 10.16cm (4inch) MEMS process. The results show that, the temperature of this chip can quickly rise to 407℃ within only 24ms, the power consumption is as low as 46mW, the working voltage is 2.85V, and the current is 16.2mA. The chip has the advantages of fast thermal response, low power dissipation and high integration.