The invention discloses a preload type six-dimensional acceleration transducer and a fault self-diagnosis method thereof, and relates to the technical field of multidimensional inertia measurement. The preload type six-dimensional acceleration transducer comprises a mass block, a housing, auxiliary plates, preload columns and branched chains, wherein the mass block and the branched chain are arranged in an accommodation chamber of the housing, the very center of each surface of the housing is provided with a threaded through hole and a U-shaped straight groove arranged at an equal distance from the threaded through hole, the side plates of the auxiliary plates pass through the straight grooves to extend out of the housing, the base plates of the auxiliary plates are arranged inside the housing, the preload columns pass through the threaded through holes to be in contact with the inner side surfaces of the base plates of the auxiliary plates, and the twelve branched chains are equally divided into six groups, and each group shares one ball hinge. The fault self-diagnosis method comprises the following steps: S1, constructing a branched chain voltage coordination equation, S2, determining whether the branched chain voltage coordination equation is established, S3, calculating a restoration value of branched chain voltages, and S4, automatically restoring a branched chain fault. According to the invention, the two problems of branched chain preloading and fault diagnosis generally existing in the prior art can be solved.