The invention discloses a shunt-wound rechargeable battery heavy constant current discharging device. The device is characterized by comprising one or more constant current discharging modules which are connected with one another in parallel by communication lines, wherein each discharging module is connected with a rechargeable battery; and the charging modules realize the coarse adjustment and fine adjustment of a discharging current by controlling the number of switches and regulating a given value of current fed to a DC converter. The device ensures high discharging current control and adjustment accuracy, has a simple structure, and can realize parallel connection among the discharging modules with different capacities and different current distribution modes such as an automatic current distribution mode, a manual current distribution mode and the like in the parallel connection.