To　enhance　the　electromagnetic　protection　performance　of　ultra-low　power　Electronic　Current　Transformer　(ECT),　a　damping　oscillatory　wave　(DOW)　disturbance　test　is　conducted　on　it.　A　method　for　generating　parallel　resonant　DOWs　is　proposed,　which　involves　two-stage　following　and　amplification　of　the　initial　waveform,　enabling　a　maximum　voltage　of　over　12V.　Finally,　considering　the　characteristics　of　the　output　signal　from　the　four-level　encoding　module　of　ultra-low　power　ECT,　electromagnetic　interference　countermeasures　combining　Transient　Voltage　Suppressor　diodes　with　RC　low-pass　filters　are　proposed.　Experimental　results　show　that　the　four-level　encoding　module　is　extremely　sensitive　to　voltage　fluctuations　due　to　the　nonlinear　relationship　between　the　voltage　and　current　of　the　LED.　The　normal　operation　of　the　four-level　encoding　module　can　be　ensured　through　anti-interference　measures.　©　2025　IEEE.