Based on the requirements of sample detection period, the soluble starch was used as diluent and binder for sample preparation of pressed powder pellet. A series of silicon-manganese alloy samples with certain content gradient, which were similar to the samples in composition, structure and particle size, were selected as the calibration samples after determining the contents of silicon, manganese and phosphorus using the national standard methods. The contents of silicon, manganese and phosphorus in silicomanganese alloy were determined by energy dispersive X-ray fluorescence spectrometry. The optimized sample preparation conditions were obtained through orthogonal tests: 4.0000g of sample and 0.4000g of soluble starch were mixed uniformly for sample preparation under pressure of 30t. The prepared pellets were uniform and smooth with moderate strength, and the reproducibility was good. The results of precision test showed that the relative standard deviation (RSD, n=10) for silicon, manganese and phosphorus in silicon-manganese alloy was 0.59%, 0.19% and 5.7%, respectively. The accuracy results indicated that the determination values of experimental method were consistent with those obtained by national standard methods, which could meet the requirements of rapid detection at the site of smelting.