The invention discloses a micro-power-consumption power supply system based on line load current sensing power taking and a working method. The micro-power-consumption power supply system based on line load current sensing power taking comprises a CT sensing power taking unit, a rectification unit, an overpower protecting circuit and an electric energy collecting circuit which are successively connected, wherein the overpower protecting circuit comprises a silicon controlled rectifier; one end of the silicon controlled rectifier is connected with a first output end of the rectification unit and an anode of a diode; the other end of the silicon controlled rectifier is connected with a second output end of the rectification unit; a capacitance energy battery, an overpower protecting and monitoring unit and an electric energy collecting circuit is connected between a cathode of the diode and the second output end of the rectification unit in parallel; the second output end of the rectification unit is grounded; and a control end of the silicon controlled rectifier is connected with the overpower protecting and monitoring unit. The micro-power-consumption power supply system based on line load current sensing power taking is economical and practical, a multi-channel power management system is adopted, CT power taking maximum efficiency point tracking, backup batteries and super-capacitor management are integrated, and intelligent power supply switching management is implemented.