The invention discloses a method for detecting and evaluating design bearing capacity of a pile foundation of an offshore oil platform. The method comprises the following steps of: (1) installing a plurality of pairs of force and acceleration sensors on the detection section of the pile foundation before piling; (2) performing first re-piling detection after piling, and evaluating the bearing capacity of the pile foundation at the moment; (3) performing second re-piling detection, and evaluating the bearing capacity of the pile foundation at the moment; and (4) detecting the design bearing capacity of the pile foundation of the platform. According to the method disclosed by the invention, with the help of field high strain dynamic test and theoretical analysis and calculation, the time-based change law of the bearing capacity of the pile foundation is obtained and serves as the basis of detecting and judging the design bearing capacity of the pile foundation; whether the bearing capacity of the pile foundation before load is applied to the platform meets the requirements on the design bearing capacity is evaluated scientifically; the method has the characteristics of operation simplicity and convenience, low investment cost, short detection period and high reliability; in the aspect of hammering energy, a processing method under the action of lower energy hammering is provided; and therefore, the evaluation result is closer to the objective reality.