The invention provides a moistureproof treatment method for soft capsules. By the method, the problems that soft capsules for filter sticks are in contact with air, continuously absorb moisture from the air and are softened, adhered and the like because of being affected with damp, so that the quality, appearance and application of the soft capsules are influenced are solved, and the requirements that the soft capsules which are embedded in the filter sticks and are used for enhancing aroma and humidifying can be moistureproof and are easy to break are met. According to the method, polyvalent metal salts are added into soft capsule wall materials and are reacted with chitosan, so that water-insoluble chitosan metal salt chelates can be formed through the reaction between the metal salts and the chitosan and are coated on the outer surfaces of the soft capsules, the waterproof performance of the soft capsules is greatly improved, the water resistance and moisture resistance of the soft capsule wall materials are improved, the brittle characteristics of the soft capsules are kept, the retention time of the filter sticks is prolonged, and the influence of an external environment on the quality, appearance and application of the soft capsules is reduced.