A method for detecting and locating fire based on double-waveband image includes: performing background modeling using a way of weighted average, and greatly reducing an amount of calculation while ensuring real time updating of a scene; performing a flame suspected region detection based on a method of frame difference, to possibly detect more flame suspected regions; excluding unqualified suspected regions according to sensory features, airspace variability feature, time domain continuity feature, position derivable feature and distribution isolation feature of the flame, to reduce phenomenon of false reports; using a method of margin marking to map the flame region detected on an infrared image to a color image for the convenience of the monitoring staff to observe; and obtaining horizontal and vertical distances of an actual ignition point with respect to a certain reference object on the ground according to a coordinate of the flame in the image to achieve an aim of locating a fire. The advantages of the present invention are: being capable of in time and accurately determining the flame feature of the monitored occasion, providing a fire alarm, transmitting a most visual video image and targeting the fire scene.