During　the　pulsed　discharge　process　in　water,　the　impedance　characteristics　of　the　plasma　channel　can　be　influenced　by　adjusting　electrical　parameters,　electrode　spacing,　pressure　levels,　and　other　factors.　Understanding　how　to　adjust　the　impedance　value　of　the　discharge　circuit　is　crucial　for　achieving　a　more　stable　and　efficient　discharge　process,　which　holds　significant　engineering　significance.　In　order　to　investigate　the　variation　trends　of　impedance　characteristics　of　the　plasma　channel　under　different　discharge　conditions,　this　study　independently　developed　a　needle-needle　electrode　high-voltage　discharge　system　in　water.　This　study　measured　relevant　electrical　parameters　such　as　voltage　and　current　of　the　plasma　channel,　and　using　circuit　formulas　and　the　particle　swarm　optimization　(PSO)　algorithm,　the　impedance　variations　of　these　five　cycles　under　different　discharge　conditions　were　investigated.　Circuit　formulas　and　the　PSO　algorithm　were　usedto　investigate　the　impedance　variations　of　these　five　cycles　under　different　discharge　conditions.　The　results　indicate　that,　under　the　experimental　conditions　of　this　study,　the　impedance　values　across　the　five　cycles　exhibit　an　increasing　trend.　When　the　voltage　amplitude　increases,　the　resistance　of　the　plasma　channel　shows　a　decreasing　trend;　when　the　pressure　level　increases,　the　resistance　of　the　plasma　channel　shows　an　increasing　trend;　and　when　the　electrode　gap　increases,　the　resistance　of　the　plasma　channel　also　exhibits　an　increasing　trend.　Additionally,　this　study　simulated　the　corresponding　oscillating　waveform　based　on　the　plasma　impedance　values　and　voltage　formulas.　By　comparing　the　fitting　degree　between　the　actual　waveform　and　simulated　waveform,　the　calculated　impedance　characteristics　obtained　in　this　study　were,　furthermore,　validated　as　reasonable.　©　1973-2012　IEEE.