The 《IDA Desalination Inventory-2002》 shows that distillation (MSF is in the majority) was domination over the desalination processes before 2002.However,the reverse osmosis (RO) is dominating in the new century.The desalination plants have spread all over the world instead of Middle-East only.The RO is the most important option for desalination in the world except the countries in the Middle-East.The distillation processes in North American municipal desalination is very limited,and the low-pressure membrane processes (MF,UF and NF) have been used at large scale in municipal water treatment and pre-treatment of desalination process.The technology of RO concerned is growing up in China.It is necessary to bulid some large scale desalting plants for alternate municipal water supply in the coast economy developed cities and, at same time,to join the international co-operation.