Calcite is one of the most common gangue minerals in mineral processing. The efficient separation of calcite from valuable minerals has long been a focus and challenge in the field of mineral processing, and especially in the processing of calcium-containing minerals such as scheelite, fluorite, and apatite. In acidic pulp, calcite could react with hydrogen ions to form CO2 bubbles, which are sometimes beneficial for minerals separation. The process of CO2 bubble generation by the reaction between calcite and sulfuric acid was systematically studied using high-speed camera in this work. The effect of sulfuric acid concentration and calcite particle size on CO2 bubbles production, bubble growth rate, detachment diameter, quantity distribution, apparent specific gravity of calcite particles and surface morphology after reaction of calcite with sulfuric acid were investigated. When calcite encountered acid, CO2 bubbles generated immediately on the surface of calcite. Once grew to a certain size, these bubbles would detach quickly from the calcite surface. When sulfuric acid concentration was in the range of 1.0wt%?2.0wt%, CO2 bubbles production on the calcite surface was inversely proportional to sulfuric acid concentration. The higher the concentration, the less CO2 bubbles was produced, and the faster the reaction terminated. As sulfuric acid concentration increased, the bubble growth rate increased and the detachment diameter reduced. The surface of the calcite would always adsorb CO2 bubbles during the reaction time, resulting in a smaller apparent weight of calcite and the change of surface properties of calcite. Calcium sulfate crystals were formed by the reaction of calcite with sulfuric acid, which prevented the further reaction of calcite with acid. The apparent specific gravity of calcite varied with the particle size, but only at small values of 6?7 seconds. The research of this work provided a fundamental basis for the separation of calcite from other non-carbonate minerals.