The invention discloses a ventilation and dehumidification system for a villa basement and a method thereof. The ventilation and dehumidification system comprises a light well skylight, a light collecting column, a solar energy water-air heat collecting column, an unpowered air cap, a solar energy water storage tank, a fan and a dehumidifying pipeline system, wherein the light well skylight is arranged on a basement roof, the light collecting column is arranged on the basement roof, and the dehumidification pipeline system communicates with a basement and the basement roof; fixing glass is arranged on the lighting well skylight, and a hole is formed in the middle; the light collecting column is arranged above the hole, and the solar energy water-air heat collecting column is connected above the light collecting column; the air heat collecting column is a multilayer round column with good light transmission, the center of the air heat collecting column is a hollow round column, and water tanks, air boxes and heat collection coating vacuum tubes are sequentially arranged in the solar energy water-air heat collecting column from inside to outside; the diameters of the hole, the lightcollecting column and the solar energy water-air heat collecting column are the same with the diameter of the hollow cylinder; and the water tanks of the solar energy water-air heat collecting columnis connected with the solar water storage tank. The unpowered air cap is arranged above the hollow cylinder of the air heat collecting column. According to the ventilation and dehumidification system,the good ventilation and dehumidification functions of the villas basement are achieved.