In view of the wide and scattered distribution characteristics of straw burning areas,remote monitoring can provide great help for scientific management and safe production,and can efficiently handling emergencies in real time and reduce losses in the event of fire alarm and pollutant discharge.Based on the above requirements,the infrared zoom optical system is proposed in this paper to monitor the abnormal situation in the straw incineration area,the zoom range is 34.5～77.5mm,and the zoom system is optimized based on Cook′s three piece optical structure.Through the optimization of optical system,the resolution of the ground scene is better than 1 m when the imaging distance is 100～2000 m,the signal to noise ratio (SNR) of the system is 34.53～70.34 and the MTF of the zoom lens at zoom process is all above 0.4 at the Nyquist frequency.Clear imaging in the range of 100～2000 m is achieved.