This book mainly introduces how to measure and analyze electric charge accumulation in Dielectrics. By using the PEA and Q(t) methods with the Quantum Chemical Calculation, the charge characteristics of solid dielectrics under different situations are analyzed, which are never discussed in detail by other books. The book contains a large number of experimental and simulation data as illustrations, and thus the reader can understand the theory in the book very easily. Meanwhile, the reader can learn how to use the two methods to measure charge behavior under different conditions and analyze the charge phenomena by Quantum Chemical Calculation.