This paper takes the connecting chain of φ32×140×60×3 narrow gauge vehicle in Xingdong Mine as the research object, and introduces the method and evaluation standard of double maximum static load experiment in the detection of connecting chain in detail. The finite element analysis software is used to analyze the performance of the force process of the connecting chain, and the key inspection parts in the detection of the connecting chain are found out. By establishing models of different chain ring diameters, it is shown that the elongation is negatively correlated with the chain ring diameter. These research results provide a theoretical reference for the strength design of the connecting chain, and also guide the detection work.