Abstract: Synthesized the experimental methods in the national standard GB/T 6155-2008 and GB/T 5071-1997, then a new way for the testing method of true density was gotten(synthesized method for short).The respective true density which were gotten by synthesized method of silica brick and petroleum coke were 2.337 0 g/cm3 and 1.816 8 g/cm3, when the results got by national standard were 2.335 0 g/cm3 and 1.817 2 g/cm3, and there were little different between the results of two methods. The conclusion compared two methods was that: synthesized method was more quick, safe and exact at the same time, and it can be used in carbon material and other material such as refractory and so on.