The bisphenol A preparing process includes reacting phenol and acetone in the reaction area with condensation reaction catalyst to obtain material flow containing bisphenol A; eliminating light component and concentrating the material flow in the light component eliminating and concentrating area to obtain product fraction containing bisphenol A and phenol as main components; separating the friction in crystallizing purification area to obtain bisphenol A product; and returning the water-poor fraction from the light component eliminating and concentrating area to the reaction area. Returning the water-poor fraction to the reaction area can lower the water content in the reaction area, ensure the activity of the catalyst, control reaction temperature raise and thus raise the acetone converting rate and reaction selectivity.