The invention discloses a power operation maintenance and preventive test early-warning system for a 35KV power distribution system, and the system comprises a data collection sensor which is disposedon a to-be-monitored object, wherein the output end of the data collection sensor is connected with a data module. The data module comprises a central processing unit and a memory; and the central processing unit is in signal connection with the memory through a bus. A self-diagnosis module and a pre-judgment module are arranged in the memory, and a protection set value is preset in the self-diagnosis module. The central processing unit in the data module compares the received data with the protection set value, and outputs a control signal through a comparison result, wherein the control signal is fed back to the control end of the power transformation equipment or the power distribution equipment through a communication line.