Abstract: Comparative studies on sample dissolution methods of six kinds of solid wastes such aselectroplating sludge, tailings,chromium,arsenic-calcium and lead-zinc slags and powder coal ash-es were carried out.The three methods were 1)conventional open vessel digestion using a hot plate,2)high-pressure sealed vessel digestion and 3) microwave-assisted acid digestion technique, respec-tively. It is shown that method 1 )was not only tedious and time-consuming,but also difficult whenused to completely decompose some solid wastes.Compared to method 1),method 2)exhibited betterdissolution ability,but suffered from time-consuming and incomplete dissolution,too. Microwave-assisted acid digestion was best among the three methods and was characterized with convenient,rapid,effective,unnecessary close attention,less pollution and high recoveries for sample preparationof all solid wastes.