Focus on such problems as that steam dryness calculation model was complex which was inconvenient for field operators while carrying on down hole high-power steam electric heater, and running time of green electric was short, meanwhile, network electricity cost was high, a simple chart was established in this paper which could help engineers to determine appropriate electric power at different steam injection rate and different well depth to reach a designed steam dryness. A parallel double pipe structure was designed to test steam dryness after steam going through the electric heater. Comparing the field tested data with the model prediction value, the errors of pressure, temperature and steam dryness were all less than 10%. By the optimization of green electricity and network electricity to optimize steam injection rate, electricity saving of single well every day would be 7%.