Inthispaper,thecalculatingmethodoftheplasmaelectrondensitybasedontheHCNwaveformdataisintroduced.ThewaysdecidingthebasevoltageandthephasezerocrosspointsoftheHCNsignals,phaseandcomputingthedensityaredescribed.Moreover,someideasforthefurtherimprovementofthemethodarealsonoticedinthearticle.