The invention discloses a monitoring device of neutral gear sliding for a commercial vehicle, aiming at overcoming the problem that whether the vehicle is at neutral gear sliding can not be monitored in real time. The system comprises a proximity switch mounting frame (2), a proximity switch (3) and a clamping frame (4). The accurate real-time monitoring for the neutral gear sliding state when the vehicle operates can be completed by the monitoring system, and traffic accidents caused by neutral sliding can be avoided effectively.