Abstract: The pantograph catenary fault events caused by the breakage of soft positioning stay wire in small radius curve section of metro line are introduced. Causes of soft positioning stay wire fracture are analyzed. Two transformation schemes based on the stress analysis of catenary soft positioning stay wire are proposed: the first is to adopt double strand -3.5 mm soft steel wire as the standby line of soft positioning stay wire, and the existing soft positioning stay wire is reinforced and wound; the second is to use the tail branch line as the standby line. The reliability tests of both schemes meet the requirements. According to the actual situation of the line, specific suggestions for catenary soft positioning stay wire reinforcement are given.