Provided is a carbon dioxide fluidity control device comprising, a sample preparation tank, a high-pressure stirring unit, a reciprocating plunger pump and a booster pump, wherein the stirring unit comprises one or more high-pressure stirring tanks, each provided with an atomizing spray probe and a piston, wherein a discharge port of the sample preparation tank is connected to the atomizing spray probe via a plunger pump, which is connected to the piston to push the piston to reciprocate; the booster pump is connected to the high-pressure stirring tanks to provide supercritical carbon dioxide to the high-pressure stirring tank; and a discharge port of the high-pressure stirring tanks is connected to an oilfield well group. Provided is a carbon dioxide fluidity control method using the device, comprising mixing surfactants and nanoparticles with heated carbon dioxide, and injecting a microemulsion of supercritical carbon dioxide and nano-silicon dioxide into an oilfield well group.