Summary form only given, as follows. A simple-structured thermal plasma generator for waste treatment has been studied. The thermal plasma technology applied to waste treatment has undoubtedly gained high importance owing to its outstanding properties such as flexibility, compact reactor, and clean treatment. Moreover, the thermal plasma generated by AC power has some additional advantages such as simple electrode system, easy maintenance, high power capability. A prototype plasma generator which has specifications of 10-30m/sec gas velocity and 3000-5000 K temperature on the center just outside of the nozzle with the input power less than 200 kW has been designed and tested. Case studies on heat transfer, heat flow, velocity distribution, and temperature distribution using a commercial simulation package show lots of flexibility in design. The experimental results from the prototype generator show that the AC thermal plasma is easily controlled by working gas flow once it is ignited. A stabilization condition is discussed with the data from monitoring the voltage-current characteristics during the test.