This paper presents a new automatic control system that can precisely and automatically analyze complex harmonics occurring from the power distribution transformers. The proposed system consists of pre-amplification block, digital signal processing block, and real-time monitoring block. It can be applied to a development board with a microcontroller connected to a PC to monitor harmonics in real time because it can be individually affixed to a transformer. The existing expensive harmonics measurement systems take a lot of time to analyze complex harmonics. Unlike the conventional systems, since this system is accurate and automatic in measurement, it provides very low measurement errors and very small test overhead. The proposed system showed very low measurement errors of less than 0.8% as well as fast real-time measurements of approximately 23sec. for harmonics analysis as compared to external expensive equipment measurements. We hope that this new system will provide industry with a simple and inexpensive technique to control and analyze complex harmonics occurring from the distribution transformers.