The monitoring system for integrated management of on-site wastewater treatment plants(biofilter) was designed and its operation program was developed. In design process, the research on monitoring parameters which will be able to represent condition and operation of the pilot plants was accomplished, and these parameters came to reveal with ORP(Oxidation-Reduction Potential), water level, pump and power on/off. Proposed monitoring system is composed with measurement, control, communication and display device, and PCB(Prototype Circuit Boards) and microcontroller (PIC16F877) technique are applied to its design of control device for performing specific function. also, The operation program of PC setup is developed in order to provide a convenience to the manager.