A device for monitoring a state of a moving object, the device comprising: a laser scanner configured to monitor at least one moving object entering a monitoring region, by emitting a plurality of laser beams of different angles to the at least one moving object with a preset scanning frequency; and a processing unit configured to, for each moving object, determine at least one fixed point on the moving object, receive a first distance between the at least one fixed point of the moving object and an emitting position of the laser beams and an emitting angle of a corresponding laser beam, the first distance and the emitting angle of the corresponding laser beam being detected by the laser scanner at each time instance, and determine and output a relative position of the moving object with respect to the laser scanner at each time instance according to the first distance and the emitting angle of the corresponding laser beam, the fixed point is selected as a point for the laser scanner to detect and return a variable data; characterized in that the processing unit is further configured to, for each moving object, according to the determined relative position of the moving object with respect to the laser scanner , output a current relative position of the moving object with respect to the laser scanner with different time intervals or with different moving distance intervals of the moving object; wherein when the moving object moves towards the laser scanner , the smaller the relative distance between the moving object and the laser scanner is, the smaller the time interval or the moving distance interval is. a laser scanner configured to monitor at least one moving object entering a monitoring region, by emitting a plurality of laser beams of different angles to the at least one moving object with a preset scanning frequency; and a processing unit configured to, for each moving object, determine at least one fixed point on the moving object, receive a first distance between the at least one fixed point of the moving object and an emitting position of the laser beams and an emitting angle of a corresponding laser beam, the first distance and the emitting angle of the corresponding laser beam being detected by the laser scanner at each time instance, and determine and output a relative position of the moving object with respect to the laser scanner at each time instance according to the first distance and the emitting angle of the corresponding laser beam, the fixed point is selected as a point for the laser scanner to detect and return a variable data; characterized in that the processing unit is further configured to, for each moving object, according to the determined relative position of the moving object with respect to the laser scanner , output a current relative position of the moving object with respect to the laser scanner with different time intervals or with different moving distance intervals of the moving object; wherein when the moving object moves towards the laser scanner , the smaller the relative distance between the moving object and the laser scanner is, the smaller the time interval or the moving distance interval is. <EOS>