An　experimental　study　on　the　antifouling　performance　of　ultrasonic　and/or　electronic　treatment　was　carried　out　in　a　convective　heat　transfer　process　by　using　a　fouling　monitor　system.　An　ultrasonic　device　was　used　in　a　frequency　of　28　kHz　and　a　power　of　80　W,　and　a　low-voltage　electronic　processor　also　used　with　a　maximum　current　of　0.8　A　for　water　treatment.　The　experimental　results　showed　that　both　of　the　ultrasonic　and　the　electronic　treatment,　all　displayed　good　scale-inhibition　effects　for　hard　water　in　convective　heat　transfer,　and　further　the　compound　treatment　of　them　gave　much　better　antifouling　performance　at　the　same　conditions.　The　fouling　inhibition　efficiency　got　up　to　a　maximum　of　100%　by　the　treatments.　The　technical　treatment　may　change　not　only　the　amount　of　deposition　on　heat　transfer　surface,　but　also　the　morphology　of　crystals　formed　in　microscale.　The　fouling　crystal　displayed　a　clear　type　of　aragonite　of　calcium　carbonate　but　varied　obviously　with　the　treatments.　It　can　be　sure　that　the　technical　treatments　are　effective　and　applicable　in　real　heat　transfer　application　with　hard　water　as　a　working　fluid.