Abstract: Focusing on the problem of missing and false fire detection caused by environmental changes when using traditional forest and grassland fixed threshold fire detection algorithm,we propose a space-time dynamic threshold fire detection algorithm considering the spatial and temporal factors,such as season,location and type of land cover.Based on the HJ-1A/B data of the native environment and disaster monitoring and forecasting of small satellite constellation,we selecte the fire case in Heilongjiang Province.Experimental results show that the space-time dynamic threshold fire detection algorithm with the space-time adaptive feature can improve the results of fire detection.