Abstract: For the shortcomings of the traditional power supply mode of the diesel generator set for the mobile flash welding machine, a new type of power supply system for the flash welding machine is presented. It is proposed to use a super capacitor to connect to a bidirectional DC/DC power converter in parallel with a battery pack through a switch to form a battery-supercapacitor hybrid energy storage system for driving mobile flash welding machines by analyzing the working characteristics of mobile rail flash welding machine. Established the model of hybrid energy storage system and conducted simulation tests, and test through product development of system prototypethe, the results show that the new hybrid energy storage system has fast dynamic response to load power ripple and stable output, which can not only meet the power supply requirements of rail flash welding machines, but also overcome the shortcomings of the three-phase load imbalance of the traditional diesel generator power supply mode and produce exhaust gas to pollute the environment. It has many advantages such as environmental protection. The independent research and development of the system has important reference significance for the technology upgrade and innovation of China seamless rail welding equipment.