The invention relates to a surface membrane coagulation technology and a surface membrane coagulation device for removing fire coal flying ash microspheres. The device is composed of a pattern-plate-type atomizer, a flow rate meter, an ultrasonic wave driving power supply, an automatic temperature control device, a tracing heat pipeline, a condensing casing pipe, an electric heating water storage tank, a water pump and an electric deduster. According to the invention, high-temperature water is atomized into 10-20 micron single-diffusion liquid drop granules by utilizing ultrasonic waves; the saturation degree of flue gas is improved to in an ultra-saturated state, wherein the SR is greater than 1.3, and the temperature of the atomized liquid drop is controlled to be 80-90 DEG C; the temperature of liquid in the condensing casing pipe is controlled, so that the flue gas is cooled to 1-5 DEG C; steam in the flue gas is adsorbed to the outer surfaces of the microspheres by utilizing the high adsorption performance of the surfaces of the microspheres, and micro bulges on the surfaces of the microspheres are taken as cores, and 'sphere'-shaped coagulation is formed rapidly, so that the specific resistance of the microspheres is reduced by 1-2 dot products; the retention time of the atomized liquid drops in flue gas is controlled to be 300 milliseconds-1 second, and then the liquid drops are collected by an electrostatic deduster efficiently.