The invention discloses an active noise reduction method and a device therefor are disclosed. The method comprises the following steps: current error noise signals are collected periodically, the error noise signals are a sum of current primary noise signals and secondary noise signals, the error noise signals are used as reference signals for a repetitive control internal model, the reference signals are subjected to repetitive control and secondary signals are obtained, the secondary signals are subjected to electro-acoustic conversion operation, and secondary noise signals are sent out. According to the active noise reduction method, a repetitive control mode is adopted for processing the error noise signals, and therefore the secondary noise signals are obtained; problems such as weight coefficient iteration and convergence performance and the like do not need to be considered, and the method is simple in algorithm and easy to realize. The invention also discloses an active noise reduction device which can be realized via the above method, and the device also has the above mentioned advantages.