Theoretical analysis of wireless power transfer (WPT) via strongly coupled magnetic resonances (SCMR) is given on the coupled-mode theory (CMT) and circuit theory (CT). Furthermore, differences and similarities between these two theories are described. Some kinds of practical system structures are analyzed by CT, and the limitation of SCMR's application is elaborated. Aiming at different practical system structures, the matching methods are explored and the conclusions are validated by simulation.