The invention discloses an acid-soluble cement temporary plugging agent and a preparation method thereof, and belongs to the field of oil well cementation. The temporary plugging agent comprises, by weight part, 1 part of reheated magnesia, 0.5-1.0 part of magnesium chloride, 0.05-0.15 part of magnesium carbonate, 0.1-0.4 part of calcium carbonate, 0.01-0.05 part of sodium tripolyphosphate, 0.005-0.01 part of ultrafine silica, 0.01-0.04 part of ammonium phosphate, 0.01-0.05 part of a retarder, 0.03-0.06 part of a fluid loss additive, and 0.3-0.6 part of water. According to the provided acid-soluble cement temporary plugging agent, the retarder can adjust the setting time of the acid-soluble cement temporary plugging agent and makes the acid-soluble cement temporary plugging agent suitable for an oil well of 30-100 DEG C, so that it is ensued that an oil well with relatively high temperature is temporarily plugged. The fluid loss additive can improve the plugging ability of the acid-soluble cement temporary plugging agent and reduces the water loss of the acid-soluble cement temporary plugging agent, so that the plugging effect on the reservoir is ensured. The acid-soluble cement temporary plugging agent is wide in application range, good in temporary plugging effect, and suitable for large-scale popularization and application.