The invention relates to the field of traditional Chinese medicine decoction pieces, and particularly relates to semen coicis prepared decoction pieces and a preparation method thereof. The semen coicis prepared decoction pieces are prepared from semen coicis and edible oil. The preparation method of the semen coicis prepared decoction pieces comprises the following steps: cleaning the semen coicis, enabling the semen coicis to pass through 30-40 mesh sieve pores, and putting the semen coicis in 1-5L of drinking water, so that the semen coicis are swelled by soaking; fishing up the swelled semen coicis, draining off surface moisture of the semen coicis, adding the edible oil, uniformly stirring, steaming for 3-4 hours by using moderate heat till cores of the semen coicis are well-done, taking out the steamed semen coicis, airing till the surfaces of the semen coicis are bright and the semen coicis is transparent, putting the semen coicis in the sun, and slightly drying the semen coicis till the semen coicis has hardness by holding with hands; and frying for 2-5 minutes by using moderate heat till the semen coicis is popcorn-shaped, taking out, screening to remove sand, and cooling, thus obtaining the semen coicis prepared decoction pieces. The semen coicis prepared decoction pieces have the advantages that effective components in cells of the semen coicis prepared decoction pieces are rapidly dissolved out, the effects of clinically reducing blood glucose and resisting tumors are enhanced, and the irritation is reduced. The processing technology of the semen coicis prepared decoction pieces has the advantages of high efficiency, standardization, energy conservation, environmental protection and the like.