Abstract: The present invention discloses a microchannel mixer, comprising a microchannel component and a shell, wherein the microchannel component is fixed inside the shell, wherein an inlet is provided at one end of the shell for feeding liquid and gas phase materials, and an outlet is provided at the other end for discharging the mixed material; said microchannel component comprises multiple stacked sheets and several layers of oleophilic and/or hydrophilic fiber filaments filled in the crevices between adjacent sheets, wherein the fiber filaments form several microchannels between them, and the fiber filaments are clamped and fixed by the sheets. The present invention also discloses a heavy oil hydrogenation reaction system comprising the above-mentioned microchannel mixer and a heavy oil hydrogenation process.