The nuclear magnetic resonance ( NMR) has become one of the most effective tools to study the structure，dynamic processes and physical properties of molecular science，material science，life science and some other fields. We focus on the study of nuclear magnetic resonance according to the Bloch Equation and the related experimental parameters，such as resonance frequency and relaxation time. Meanwhile，the pulse sequences including Single Pulse，Inversion Recovery，Spin Echo，CPMG and etc are simulate. Thus we reveal consequently the physical origins of different pulse sequences.