The invention relates to a device which controls the crystallization appearance of compound and a method for control crystallization appearance of calcium sulphate, whose characteristic is this equipment includes the reactor (1), the circulating pump (2), the pipeline (3) and the microwave reactor (4). The bottom of the reactor (1) connects the circulating pump (2). The circulating pump connects the reactor by entering the microwave reactor though the circulating pumps (3). It puts the 0.05-0.5mol/L sulfuric acid and 0.05-0.5mol/L calcium chloride solution into the reactor (1), and then turn on the circulating pump (2), controls the speed of flow 0.02-1m/s. After that turn on microwave reactor (4) and regulates the power at 100-700W, the frequency at 915MHz or 2450MHz, the circular reactions at 10- 300min. At last, turn off the power supply and the circulating pump. The crystal can be made into different appearance after laundering and dry.