Abstract: In this paper, the research history of earthquake size measurement was reviewed in the first place. And on this basis the following points were pointed out: ① In recent decades, the M_L, m_b (m_B), M_S magnitude scales were widely used as the measures of an earthquake size. However, they not only had " overgeneralization" or " magnitude saturation" problem, but also were just inaccurate measurement because of not fully taking into account the regional differences of seismic attenuation, especially the differences of the site response on the ground motion amplification. ② The seismic moment M₀ not only has clear physical meaning, but can also overcome many scaling problems of the M_L, m_b (m_B), M_S magnitudes. It is the most suitable physical parameter for measuring earthquakes scientifically. In order to continue the term of “magnitude”, Kanamori defined the moment magnitude scale M_W, although the prerequisite assumptions remain to be studied, it is still a reasonable measure of the relative size of the earthquake. ③ For measuring earthquakes more scientifically, we must make full use of a large number of waveform data by the modern regional digital seismograph network, and strengthen the research on seismic wave attenuation characteristics, site effects, the measurement of source parameters and related scaling relations. On the basis of improving measurement methods of the M_L, m_b (m_B), M_S, we should focus on improving M_W scale in order to gradually advance M_W as a unified physical quantity to measure the earthquake relative size, it would lay a more substantial foundation for research on earthquake science and earthquake prediction.

Key words: Earthquake measurement, Magnitude, Seismic moment, Energy, Stress drop