UF water, RO water and DI water are used for carrying out soaking three times, dirt and dust are removed in a diversified mode, and it is guaranteed that manufactured cloth is free of dust. An alkaline agent is added into the UF water, then an acidic agent is added into the RO water, the two solutions can be neutralized, and it is not needed to additionally carry out acid pickling with acetic acid and other acid solutions. A proper amount of organic stabilizer is added into the UF water and the RO water, the stability of gray fabric can be guaranteed, secondary pollution in the subsequent steps is avoided, and corrosion of an alkaline or acidic solution can be avoided.