Regular high precision detection of the deformation and surface oxide film thickness of nuclear fuel assemblies has become an important measure to ensure safe operation of nuclear power plant (NPP). Aiming at the generally existed serious problems of poor passive adaption performance, insufficient contact and measurement flexibility, and urgent improvement of detection accuracy and efficiency of existing detection devices for nuclear fuel assembly, a passive adaptive flexible detection device for nuclear fuel assemblies that combines deformation and film thickness high precision detection functions together is developed through designing the adaptive aligning mechanism based on mutated hook joint, the active/passive flexible detection unit with dynamic feedback of contact force and the high precision detection mechanism based on serialparallel hybrid connection. On this basis, a measurement error compensation method based on parameter dynamic integration is proposed through deeply analyzing the deformation and film thickness detection mechanism of the device, based on the constructed serialparallel hybrid connection closedloop detection loop and integrating the probabilistic sensing error cooperative compensation strategy. The prototype experiment results show the developed device can adaptively align the nuclear fuel assembly under anisotropic random deformation, meet the requirements of flexible contact and flexible measurement in detection process. Combining the proposed measurement error compensation method, the developed device can realize the high precision detection of deformation and oxide film thickness of nuclear fuel assembly, effectively enhances the detection accuracy, efficiency and safety of nuclear fuel assemblies.