The invention relates to an experimental method for determining reaction velocity of carbonate rock and hydrochloric acid in an acidification and fracturing laboratory and a research department. The method helps overcome discontinuity of periodic sampling of an acidification and fracturing experiment and test errors of titration method and enhance the test accuracy of acid and rock reaction velocity. The technical proposal is as follows: acid liquor is displaced from an intermediate container by a displacing fluid, preheated and sent to a double-rock plate type simulated crack reactor to react with rocks on a wall; the reaction product is cooled, filtered and sent to a gas-liquid separator, nitrogen gas is injected into the gas-liquid separator to separate carbon dioxide from the liquid, the mixed gas is discharged from the separator, and is subject to dehydrochlorination by distilled water, dehydration by phosphorus pentoxide and dehydration by concentrated sulfuric acid, and then an infrared gas analyzer is employed to determine the carbon dioxide content of the mixed gas, and the total flow rate, pressure and temperature of the mixed gas are also determined, and the reaction velocity is calculated by combing a state equation and a reaction formula The experimental method has the advantages of simple and convenient operation and higher accuracy, and can be used for determining the reaction velocity of the carbonate rock and the hydrochloric acid.