The invention relates to in-situ mineralization auxiliary agents SZK and SZH and after backwashing method used in dyed slubbing after backwashing. The auxiliary agent SZK is composed of 0.001 to 10% of sulfamic acid, 0.001 to 5% of polyacrylic acid, 0.001 to 3% of potassium chloride, 0.001 to 3% of copper sulphate, and the balance water; and the auxiliary agent SZH is composed of 5 to 15% of potassium permanganate, 1 to 5% of carboxymethyl cellulose, 1 to 10% of anhydrous sodium sulfate, and the balance water. According to the after backwashing method, dyed slubbing is delivered though after backwashing bath containing the auxiliary agent SZK and after backwashing bath containing the auxiliary agent SZH successively for washing, wherein water bath temperature and concentration, and slubbing moving speed are controlled. In-situ mineralization is adopted in after backwashing process, so that advanced water-saving and emission reduction are realized; operation requirements are low; operation is simple; and popularization is convenient to realize.