A modularized active power filter includes a control module and at least one power module. The control module automatically identifies the number of parallel connected power modules and generates one set of PWM signals to correspondingly control the parallel connected power modules, so as to provide a final compensation current by a single power module or by plural power modules. Thereby, the compensation demand of a load is met. Consequently, the modularized active power filter is able to improve flexibility of compensation capacity, to shorten the time for service, to be suitable for mass production, and to lower the manufacturing cost.