The invention discloses a method for placing an A/D (Analog to Digital) converter, a positive irradiation detector and CT (Computerized Tomography) equipment. The positive irradiation detector comprises a collimator, an X-ray to visible light converter, a visible light to analog signal converter, a substrate and an A/D converter, wherein the A/D converter is used for converting an analog signal into a digital signal. The method for placing the A/D converter in the positive irradiation detector comprises the following step of: arranging the A/D converter at a position which cannot be irradiated by X-rays on the substrate. The CT equipment comprises the positive irradiation detector disclosed by the invention. Due to the adoption of the technical scheme of the invention, the A/D converter can be placed into the positive irradiation detector under the condition of keeping modification on an original detector structure minimum, the A/D converter is prevented from being irradiated by X-rays, and the A/D converter is well protected.