【Purpose/significance】In the era of big data, the public data platform has developed rapidly as an important carrier of data resource value creation, but it also faces various complex security problems. By building a scientific and effective public data platform security index, it provides evaluation criteria and quantitative evaluation tools for improving its security evaluation mechanism.【Method/process】Combining the zero trust theory, this paper proposes a three-dimensional public data platform security index analy⁃ sis framework including identity security, data security and basic security, and uses principal component analysis and analytic hierar⁃ chy process to screen indicators and calculate weights【. Result/conclusion】The results show that the index has high credibility and ef⁃ fectiveness, and it can facilitate the the country and governments at all levels to quantify the the security status of the public data plat⁃ form , and provide strategies for the security construction of the public data platform【. Innovation/limitation】This research introduces the theory of zero trust and selects the security index as the quantitative research object, aiming to innovatively break the default "trust", and provide management ideas and practical paths for improving the security of public data platforms based on the principle of "continuous verification and never trust".