At the present live-line measurement practice of non-gap metal-oxide surge arresters, there are problems of inaccurate measurement results. Especially the dominant capacitive current compensation method which brings large principal deviation without extracting potential transformer secondary signal or based on station transformer reference voltage signal, would cause false or missing judgment. Combined with specific test cases, the application and problems of the prevailing live-line measurement methods of non-gap metal-oxide surge arresters are summarized, such as capacitive current compensation method, triple frequency harmonic method and the infrared thermography method. And the corresponding solution for the above problems is discussed. An inversion method of both resistive current and harmonic current component based on the total-current harmonic waves processing is also presented, and the simulating and comparing experiments’ results show that the method accords with the safe, simple and accurate tendency of live-line measurement of arresters.