Effects of temperature and four acids(HNO3, HNO3/H2O2, HNO3/HF and HNO3/HF+H3BO3)on the coal decomposition by microwave digestion and the multi-element analysis were studied. SARM20 was used as a coal standard reference material. The contents of 10 mineral elements(Al, Ca, Fe, Mg, K, Na, S, Si, Sr and Ti)in the coal SARM20 were determined by inductively coupled plasma-optical emission spectrometry(ICP-OES). And the contents of 20 heavy metals(Li, Be, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, As, Se, Zr, Sn, Cs, Ba, Ce, Eu and Pb)were determined by inductively coupled plasma-mass spectrometry(ICP-MS). The results showed that the coal was completely decomposed by microwave digestion with HNO3/HF+H3BO3 at 210　℃. Good recoveries for all elements in the coal SARM20 were obtained by this two-step microwave digestion method. The recoveries of the 10 mineral elements were from 87.5% to 98.8%, and the recoveries of the 20 heavy metals were from 85% to 112.5%. All RSDs of tests were below 3%.