Abstract: Microwave acid digestion is the most important pretreatment method for the determination of metal elements in solid wastes by Inductively Coupled Plasma-Mass Spectrometry(ICP-MS). Different acid systems have significant influences on the results. In this study, comparative analysis results of 16 metal elements in national soil standard sample, solid waste standard samples and solid waste actual samples were carried out in four different acid systems of HNO₃-HCl, HNO₃-HF, HNO₃-HCl-H₂O₂ and HNO₃-HF-HCl-H₂O₂. The precision and accuracy of different elemental determination in HNO₃-HCl and HNO₃-HF-HCl-H₂O₂ systems were also evaluated. Results show that adding HF can improve the 40% recovery of Mo and Sb in soil matrix. Recovery of Sb in solid waste can improve 33%-50% by adding HF. In the system containing HF acid, the varied ratios of HNO₃ and HCl show no significant effect in elemental determination. However, for the Cr slag samples, the high concentration of Cr inhibited the V signals because of the space charge effect. In terms of precision and accuracy, the HNO₃-HF-HCl-H₂O₂ is considered as the best acid system for determination of metal elements in solid waste.