The present invention relates to the field of passenger conveyor technologies, and provides a monitoring system of a passenger conveyor and a monitoring method thereof. In the monitoring system and detection method of the present invention, a monitored object of the passenger conveyor is sensed by using an imaging sensor and/or a depth sensing sensor to acquire a data frame, and the data frame is analyzed by a processing apparatus to monitor whether the monitored object is in a normal state. The monitored object may include a landing plate, a step, a barrier used in a maintenance and repair working condition and/or a step speed, and the like.