A monitoring system of a passenger conveyor, comprising: an imaging sensor (310 1 - 310 n) and/or a depth sensing sensor configured to sense (S11, S21) a monitored object (903, 904) of the passenger conveyor to acquire a data frame; a processing apparatus (100, 200) configured to analyze the data frame to monitor whether the monitored object (903, 904) is in a normal state, the processing apparatus (100, 200) being configured to comprise: a background acquisition module (110, 210) configured to acquire (S12, S22) a background model based on a data frame that is sensed when the monitored object (903, 904) is in a normal state; a foreground detection module (120, 220) configured to compare (S13, S23) a data frame sensed in real time with the background model to obtain a foreground object; and a working condition judgment module (140, 240) configured to perform data processing at least based on the foreground object to judge whether the monitored object (903, 904) is in a normal state; wherein the processing apparatus further comprises a foreground feature extraction module (130, 230) that is configured to extract a corresponding foreground feature from the foreground object according to the monitored object (903, 904); wherein the working condition judgment module (140, 240) is further configured to judge, based on the foreground feature, whether the monitored object (903, 904) is in a normal state, and wherein a comparison judgment is performed on the foreground feature by comparing the foreground feature with feature information about the monitored object (903, 904) using the background model; and characterized in that: if the foreground feature is a foreground feature of a foreground object of a passenger, the working condition judgement module is configured to judge that the foreground feature is unrelated to the monitored object (903, 904), and to judge that the monitored object (903, 904) is in a normal state. an imaging sensor (310 1 - 310 n) and/or a depth sensing sensor configured to sense (S11, S21) a monitored object (903, 904) of the passenger conveyor to acquire a data frame; a processing apparatus (100, 200) configured to analyze the data frame to monitor whether the monitored object (903, 904) is in a normal state, the processing apparatus (100, 200) being configured to comprise: a background acquisition module (110, 210) configured to acquire (S12, S22) a background model based on a data frame that is sensed when the monitored object (903, 904) is in a normal state; a foreground detection module (120, 220) configured to compare (S13, S23) a data frame sensed in real time with the background model to obtain a foreground object; and a working condition judgment module (140, 240) configured to perform data processing at least based on the foreground object to judge whether the monitored object (903, 904) is in a normal state; wherein the processing apparatus further comprises a foreground feature extraction module (130, 230) that is configured to extract a corresponding foreground feature from the foreground object according to the monitored object (903, 904); wherein the working condition judgment module (140, 240) is further configured to judge, based on the foreground feature, whether the monitored object (903, 904) is in a normal state, and wherein a comparison judgment is performed on the foreground feature by comparing the foreground feature with feature information about the monitored object (903, 904) using the background model; and characterized in that: if the foreground feature is a foreground feature of a foreground object of a passenger, the working condition judgement module is configured to judge that the foreground feature is unrelated to the monitored object (903, 904), and to judge that the monitored object (903, 904) is in a normal state. a background acquisition module (110, 210) configured to acquire (S12, S22) a background model based on a data frame that is sensed when the monitored object (903, 904) is in a normal state; a foreground detection module (120, 220) configured to compare (S13, S23) a data frame sensed in real time with the background model to obtain a foreground object; and a working condition judgment module (140, 240) configured to perform data processing at least based on the foreground object to judge whether the monitored object (903, 904) is in a normal state; wherein the processing apparatus further comprises a foreground feature extraction module (130, 230) that is configured to extract a corresponding foreground feature from the foreground object according to the monitored object (903, 904); wherein the working condition judgment module (140, 240) is further configured to judge, based on the foreground feature, whether the monitored object (903, 904) is in a normal state, and wherein a comparison judgment is performed on the foreground feature by comparing the foreground feature with feature information about the monitored object (903, 904) using the background model; and characterized in that: if the foreground feature is a foreground feature of a foreground object of a passenger, the working condition judgement module is configured to judge that the foreground feature is unrelated to the monitored object (903, 904), and to judge that the monitored object (903, 904) is in a normal state.