The invention relates to a condensation type oil field steam-injection boiler flue gas waste heat recovery device and method. According to the technical scheme, a heat preservation fixing piece is welded to the inner wall of a pipe ring support to be used for fixing an inner heat preservation layer, a heat absorbing pipe set is connected into a water feeding flowing channel by welding a finned pipe and a bend and comprises an upper pipe set and a lower pipe set, and a flue gas even distribution flow guide plate and a condensation water collecting plate are welded and fixed to the pipe ring support in an inclined manner; after flue gas absorbs heat through the lower pipe set of the heat absorbing pipe set, the temperature of the flue gas has already been reduced to the flue gas dew point when the flue gas reaches the flue gas even distribution flow guide plate and the condensation water collecting plate, then the flue gas enters the upper pipe set through the flue gas even distributionflow guide plate and the condensation water collecting plate to flow in an Z-type turning manner, water vapor in the flue gas becomes the liquid state from the gas state, and therefore latent heat inthe flue gas is released. The condensation type oil field steam-injection boiler flue gas waste heat recovery device and method have the beneficial effects that waste heat of the water vapor in the flue gas is recovered, the boiler water feeding temperature is improved, the flue gas discharge temperature is decreased, the boiler heat efficiency is improved, the structure is compact, and installation, maintaining and replacement are easy.