The invention discloses an unrestraint type trolleybus power system suitable for urban areas and expressway sections. The unrestraint type trolleybus power system comprises a trolleybus, a fixed typewire plate, contact rollers, a connection plate, a mounting column, a live wire, a metal band and a pre-embedded null wire; the mounting column is arranged on a road; the fixed type wire plate is arranged at the upper end of the mounting column and arranged above the road in a mode of being hung in the air; the lower surface of the fixed type wire plate is covered with conductive metal and electrified; the connection plate is arranged on the top of the trolleybus, the lower side of the connection plate is connected with the trolleybus through damping springs, the upper side of the connection plate is connected with the fixed type wire plate through the contact rollers, and the connection plate is connected with a trolleybus engine of the trolleybus through the live wire; the pre-embedded null wire is arranged in the road; and the metal band of the trolleybus engine is hung in the air and makes contact with the pre-embedded null wire. According to the unrestraint type trolleybus power system, the situation that an existing trolleybus can only travel separately along an overhead electricity supply contact wire is avoided, parallel travelling of multiple trolleybuses is achieved, thecurrent situation that overtaking of the existing trolleybus cannot be achieved is changed, and the flexibility of the trolleybus is improved.