The invention discloses a preparation process of a waterproof flame-retardant polyamide fiber fabric, which solves the problem in the prior art that a pretreatment way capable of well ensuring the dyeing effect of synthetic fiber fabric cannot be found. The preparation process comprises a pretreatment process and a printing and waterproof flame-retardant layer coating process, wherein the pretreatment process comprises the following steps: cold rolling a gray fabric, boiling the fabric, and stereotyping the fabric, wherein when in cold rolling, caustic soda with the concentration of 35 to 45 g/L and hydrogen peroxide with the concentration of 6 to 10 g/L are used for padding the gray fabric; when in boiling, the immersion is performed in a five-time immersing and five-time rolling manner,and then the fabric is steamed; immersion additives comprise a desizing refining agent, a chelating agent, caustic soda, hydrogen peroxide and water galss, wherein the concentration of the desizing refining agent is 3 to 5 g/L, the concentration of the chelating agent is 1 to 3 g/L, the concentration of the caustic soda is 8 to 12 g/L, the concentration of the hydrogen peroxide is 4 to 6 g/L, andthe concentration of the water glass is 4 to 6 g/L; and when in the stereotyping, the speed is 85 to 95 m/min, and the temperature is 180 to 200 DEG C. The preparation process has the advantages of good dyeing effect, more stability in adhesion of a waterproof flame-retardant layer and the like.