Discharge printing process of polyester fabric

The invention relates to the field of fabric printing, and discloses a discharge printing process of a polyester fabric. The discharge printing process comprises the following steps that S1, dyeing iscarried out, specifically, a gray fabric is dyed; S2, primary washing is carried out, specifically, the gray fabric treated in the step S1 is washed; S3, drying and shaping are carried out, specifically, the gray fabric treated in the S2 is dried and shaped; S4, printing is carried out, specifically, the gray fabric treated in the S3 is printed, wherein a sizing agent used in the printing processis prepared from the following chemical components in parts by weight: 20-40 parts of stannous chloride, 4-8 parts of a cosolvent, 100-140 parts of starch paste, 20-50 parts of vat dye and 13-18 parts of sodium diethyl hexyl sulfosuccinate; S5, ageing is carried out; S6, secondary washing is carried out; and S7, after-treatment is carried out, specifically, the printed polyester fabric is obtained after the S7. Sodium die