A boiler-water treatment device main composed of solar energy heater and reverse osmosis was designed Experiments on permeation flow and water quality as functions of temperature caused by solar energy were conducted. The experimental results showed that when the operation pressure was kept at 0.9MPa, permeation flow could increase 35.5%, from 6.5L/min to 8.8L/min if the feed water temperature increased from 18°C to 38°C by solar energy; and the produced water could totally meet Chinese water quality standard for middle or low pressure steam-boiler. On the other hand, if the permeation flow was kept at 8 L/min, the operation pressure would drop by 32.2%, from 1.18MPa to 0.78MPa. Based on these experimental results, economic and environmental analysis on a case of 10m3/h boiler-water treatment device by reverse osmosis employing solar energy were conducted, the results shows great significance for energy saving and environmental pollutants cut. All this showed this new RO system with pre-heating the feed water by solar energy could be widely applied in boiler-water treatment.