A step roller monitoring system of a passenger conveyor, comprising: an imaging sensor (310 1 -310 n) and/or a depth sensing sensor configured to sense at least a part of the step rollers of the passenger conveyor to acquire data frames; and a processing device configured to analyze and process the data frames to monitor whether the movement of an operating step roller and/or a position of a static step roller is in a normal state, wherein the normal state refers to that the movement and/or position of the step roller is in a predetermined trajectory pattern; characterised in that the processing device further comprises: a target object detector configured to detect a target object related to the step roller from the data frames; a position feature extraction module configured to extract a position feature based on the detected target object; a trajectory generation module configured to generate a movement trajectory related to the target object according to position features of the target object that are obtained corresponding to the plurality of continuous data frames; and a state judgment module configured to judge whether the movement trajectory is in the predetermined trajectory pattern, and determine that the movement of the step roller and/or the position of the static step roller is in the normal state when the judgment result is "yes". an imaging sensor (310 1 -310 n) and/or a depth sensing sensor configured to sense at least a part of the step rollers of the passenger conveyor to acquire data frames; and a processing device configured to analyze and process the data frames to monitor whether the movement of an operating step roller and/or a position of a static step roller is in a normal state, wherein the normal state refers to that the movement and/or position of the step roller is in a predetermined trajectory pattern; characterised in that the processing device further comprises: a target object detector configured to detect a target object related to the step roller from the data frames; a position feature extraction module configured to extract a position feature based on the detected target object; a trajectory generation module configured to generate a movement trajectory related to the target object according to position features of the target object that are obtained corresponding to the plurality of continuous data frames; and a state judgment module configured to judge whether the movement trajectory is in the predetermined trajectory pattern, and determine that the movement of the step roller and/or the position of the static step roller is in the normal state when the judgment result is "yes". a target object detector configured to detect a target object related to the step roller from the data frames; a position feature extraction module configured to extract a position feature based on the detected target object; a trajectory generation module configured to generate a movement trajectory related to the target object according to position features of the target object that are obtained corresponding to the plurality of continuous data frames; and a state judgment module configured to judge whether the movement trajectory is in the predetermined trajectory pattern, and determine that the movement of the step roller and/or the position of the static step roller is in the normal state when the judgment result is "yes".