Abstract: This paper firstly summarized the characteristics of seismic intensity and its abnormality. Then, based on the analysis on the damage information of several intensity abnormal regions, the paper made a detailed summary of the abnormal intensity's formation mechanism and distribution rule associated with terrain feature, soil characteristics, faults, soil structure and underground water level. Finally， the paper made a systematical summary on the abnormal intensity research progress from macro-inspection, field testing, seismic record analysis and numerical simulation. In general, at present stage the research on intensity anomaly has not been comprehensive, mostly based on macroscopic seismic damage data, regional geological structure and local site conditions. The research results can not fully explain the causes of abnormal intensity, being mostly qualitative, instead of quantitative, analysis, especially lacking of strong motion record analysis. This paper has put forward a proposal to develop further research on the abnormal intensity's formation mechanism, distribution law and damage effect.