Abstract: Aiming at the problem of high viscosity and difficult dehydration of the heavy oil during the exploitation and utilization，based on the principle of microwave thermal effect and non-thermal effect，it is investigated by using high power microwave radiation experimental equipment designed by ourselves，and analysed on influence of microwave radiation power and time on the dehydration rate，radiation effect on resin and asphaltene，and described in detail the process of technology. The results showed that：microwave de?hydration is 90.7% on average，the microwave technology compared with conventional heating technology，which is 34.8% on average，microwave dehydration rate is much greater than conventional heating technology；After frequency of 915 MHz，1 kW power microwave radiation for 1min（thermal effects），temperature quickly raises to 71.2 ℃，fast response；after microwave radiation（non- thermal effect），using SARA determination method，the oil sample asphaltene content is reduced by 2.5% and resin content is reduced by 1.2%，oil viscosity changed significantly in the low temperature region. It is shown that microwave technology provides an important reference and has a better application prospect in the field.