Intelligent release is core control unit of intelligent appliances, which is used to protect power system and power devices from damage under the faults. In this paper, with LPC2478 as Microcontroller, an intelligent release control unit with Ethernet communication functionality was presented. The intelligent release control unit’s basic functions and extended functions were described in brief. Implementation method of control unit was illustrated in detail. Process flow chart for fault diagnosis was supplied. Full-wave Fourier algorithm was adopted to compute fundamental components and harmonic components to filter decaying DC component and non-integer harmonic. This release can be adjusted according to the requirement of power quality to avoid malfunction under the circumstance that non-fault current and voltage fluctuation occur. Furthermore, through Ethernet communication, more functionality can be implemented to make the release more intelligent.