Shale gas, as one kind of unconventional gas, is an important energy supplement. The pore structure characteristic is an important index using to measure and evaluate shale reservoir quality. The Weiyuan marine shale, Jiao Shiba marine shale and Yaoqu continental shalewere selected to study the pore structure characteristics and controlling factors using cold field emission scanning microscopy (FE-SEM). Nuclear magnetic resonance cryoporometry (NMRC) was employed to represent nano-scale pore structure. This method can be extended to microns measurement combining nuclear magnetic resonance relaxation analysis to detect in detail the pore structure of shales under the different aperture scales. The smaller the test temperature gradient is, the finer the result of pore distribution is.. NMRC, mercury intrusion porosimetry (MIP) and gas adsorption (GA) methods show good agreement of pore distribution in their respective scope of application. NMR method results in a much better estimate for the total pore volume than the more common MIP and GA. Hence, the pore structure of the reservoir shale can be evaluated more accurately by combining NMRC, LFNMR with GA and MIP. Thus the nano-pores of continental shale are clearly better developed and will more likely have a higher commercial exploitation value than marine shale.