Abstract: It is important to select the suitable equation of state in the research process of evaluating storage performance of ANG (adsorption natural gas). Five different equations of state, ideal gas EOS, Virial EOS, Peng-Robinson (PR) EOS, RedlichKwong (RK) EOS, and Soave-Redlich-Kwong (SRK) EOS, are given in the paper. The volumetric method test device has been used to investigate the applicability of various equation of state in the case of methane adsorption storage. In the case of room temperature, 0~8 MPa, the relative deviation of volume ratio is at 10.097%, 1.230%, 1.475%, 2.288 % and 0.248% when the ideal gas/SRK/PR/Virial/RK equations of state have been used respectively.The minimum relative deviation is obtained when the RK equation of state is adopted. And it is completely suitable for the study of methane adsorption storage. If the test pressure is not more than 4 MPa, the Virial and SRK equation of state will be also applicable.