The invention discloses a method for preparing docusate sodium soft capsules, which comprises the following steps: A, preparing red gelatin solution, i.e. dissolving a plasticizer into water, adding the obtained product into a gelatin melting tank, heating to a temperature of 40 to 80 DEG C, adding gelatin, stirring to dissolve the gelatin to obtain gelatin solution, adding a colorant I into the water, uniformly stirring, adding the mixture into the gelatin solution, stirring, vacuumizing and discharging air bubbles to obtain the red gelatin solution for later use; B, preparing white gelatin solution, i.e. adding an additive into the sufficient quantity of water, uniformly dispersing by a colloid mill to obtain solution I, dissolving the plasticizer into the water, adding the solution I and the plasticizer solution into the gelatin melting tank to heat to a temperature of 40 to 80 DEG C, adding gelatin, stirring and dissolving the gelatin, and after totally dissolving the gelatin, vacuumizing and discharging air bubbles to obtain the white gelatin solution for later use; C, preparing contents, i.e. adding polyhydric alcohol into polyethylene glycol solution of docusate sodium and uniformly mixing at a temperature of 30 to 50 DEG C to obtain the contents for later use; and D, preparing the soft capsules, i.e. adding the content liquor obtained in the step C into a feed hopper of a pelleting press, regulating packing volumes and thickness of shells, pelleting, drying, smearing pills and packaging.