The invention discloses a semi-automatic line maintenance device which mainly comprises a small round clamping ring, a big round bottom ring and an operation device and further comprises a plug-in mounting locking mechanism, a leveling mechanism, a tail section locking device, a hinging locking device, a feeding mechanism, a lifting driving device and a swing driving device. The semi-automatic line maintenance device can be quickly assembled on site, quickly calibrated and quickly leveled, is simple to adjust, can automatically paint and code electric poles and smear slogans, can quickly measure verticality or inclination degree of the electric poles, can be quickly docked with triphase wires of the electric poles and collect detection data and is simple and convenient to demount, small inoccupied space after demounting, convenient to carry, time-saving and labor-saving, and the whole operation can be completed by one person only.