The key to beryllium-determining in coal, geochemical samples, soil, air and other different substrates by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) is to choose a proper matrix modifier. The coal sample is slow burning ashed and then determined by integration platform graphite tube. In this paper, the sensitization effect of seven kinds of matrix modifier (lanthanum nitrate, magnesium nitrate, aluminum nitrate, diammonium phosphate, palladium chloride, calcium carbonate, tartaric acid) to beryllium in nitric acid solution is contrasted, and the elimination of matrix interference is discussed. The experimental results show that the interference of coexisting elements, such as aluminum, iron, calcium, magnesium and phosphorus, are eliminated under the condition of 2% nitric acid medium, lanthanum nitrate as matrix modifier, 1100℃ of ashing temperature and 2300℃ of atomization temperature. The limit of detection is 0.008 μg/L, the limit of quantification is 0.025 μg/L and the linear measurement is 0-8 μg/L. The RSD (n=11) of standard determination is 1.8%-2.8%, the measured values of standards are within the given range. The mechanism is lanthanum and interference elements combined to generate the thermal stability of refractory are indissoluble and difficult to evaporate to release beryllium. Lanthanum can not only improve the ashing temperature, but can also lower the atomization temperature to eliminate the matrix interference and prolong the service life of the graphite tube. This method is simple and less expensive than traditional methods, with strong stability and adaptability, and without pretreatment of graphite tubes. It is suitable for the determination of beryllium in coal.