Purpose:This paper intends to explore methodologies and indicators for the analysis of overlapping structures and evolution properties in a co-citation network,and provide reference for overlapping structure analysis of other scientific networks.Design/methodology/approach:The Q-value variance is defined to achieve overlapping structures of different levels in the scientific networks.At the same time,analyses for time correlation variance and subject correlation variance are used to present the formation of overlapping structures in scientific networks.As a test,a co-citation network of highly cited papers on Molecular Biology & Genetics from Essential Science Indicator (ESI) is taken as an example for an empirical analysis.Findings:Our research showed that the Q-value variance is effective for achieving the desired overlapping structures.Meanwhile,the time correlation variance and subject correlation variance are equally useful for uncovering the evolution progress of scientific research,and the properties of overlapping structures in the research of co-citation network as well.Research limitations:In this paper,the theoretical analysis and verification of time and subject correlation variances are still at its initial stage.Further studies in this regard need to take actual evolution of research areas into consideration.Practical implications:Evolution properties of overlapping structures pave the way for overlapping and evolution analysis of disciplines or areas,this study is of practical value for the planning of scientific and technical innovation.Originality/value:This paper proposes an analytical method of time correlation variance and subject correlation variance based on the evolution properties of overlapping structures,which would provide the foundation for the evolution analysis of disciplines and interdisciplinary research.