Abstract: The pretreatment of plants samples is rather complicated，timeconsuming，cumbersome，and energyconsuming.In this study，the high permeability of microwave heating is used in the digestion and extraction of sweet potato samples with 1 molL hydrochloride as a solvent.With the 20 percent of the strontium chloride as the testudo for silicon and phosphorus interference ions，the calcium purity in the sweet potato extract was determined by using atomic absorption spectrometry.The effects of the ratio，the microwave power and the extraction time on the calcium extraction were discussed.Each factor was optimized by orthogonal test：the ratio is 1∶70，the microwaveassisted extracting time is 5 min and the extracting power is 440 W.Compared with the conventional method，the microwaveassisted method is simple，less energyconsuming，and less timeconsuming.The extraction result is satisfactory，and can be applied to other plant extraction.