Abstract: 【Purpose/significance】Collaboration is an important way of scientific research at present, and the existing research on sci?
entific collaboration ignores the important form of academic collaboration in joint postgraduate training. It is of great significance to
clarify the formation mechanism and evolution characteristics of collaboration between supervisors in joint postgraduate training for a
deep understanding of scientific collaboration and cooperative behavior of supervisors.【Method/process】Taking the three institutions
with the largest collaboration scale in the statistics discipline as an example, this paper constructs directed networks by collaboration
between supervisors based on the dissertation data under the joint postgraduate training and uses social network analysis to explore the evolution law and structural characteristics of networks from the macro and micro. Based on the exponential random graph model, the formation mechanism of collaboration is clarified from two aspects of network structure and supervisor's personal attributes.【Result/conclusion】The supervisors collaboration networks in the three universities have similar evolution trend, and show the characteristics of cluster, chain structure and multiple small community structure respectively in overall structure. The structure effect on the network formation is different among universities. Reciprocity and mediation promote the formation of collaboration, while closeness shows no effect on the formation of collaboration. There is no matching tendency in the research direction of supervisors, and attribute effects such as title of supervisor have a significant positive influence on network formation.【Innovation/limitation】This paper expands the research perspective of scientific collaboration and provides a reference for the discovery of collaboration laws and the exploration of the formation mechanism of collaboration between supervisors in joint postgraduate training. The applicability of the conclusion to other disciplines and special situations such as the inter-institutional and inter-disciplinary collaboration of supervisors remains to be investigated.