Sustained and deepened aridization process in northwest China in Tertiary and Quaternary period and time of mankind history is discussed in the paper. The rain-creased function of 3 set high mountain condensation systems in northwest China is recognized once more. A sandstorm happened in March 20 this year in Alxa and Ejin(Qi) areas was very strong and arrived in Jappen and Korea. For saving Alxa area from sandstorm a way of introducing sea water from Bohai to Alxa had been proposed. Four problems are replied in this paper. In couclusion, introducing sea water from Bohai Sea to west China is the best way for sustainable development of west China.