With the development of underwater archaeology in China, scientific conservation of underwater cultural relics becomes more and more important. It is difficult to remove the different kinds of attachments on the surface of underwater porcelain. Current mechanical and chemical methods have their own limitations. Due to its long existence time, high mass transfer efficiency and high zeta potential of surface charge, micronano bubble cleaning technology has shown great effectiveness on underwater porcelain in cleaning tests. This makes it essential to evaluate its safety in the next stage. Eighteen porcelain shards samples from the Nanhai I shipwreck were selected for the evaluation. Condition survey and diagnostic analysis were made, colorimetric analysis, gloss analysis, microscopic analysis and microscopic measurements were used. The results gave no indication that micronano bubble cleaning would lead to the change of color or gloss of underwater porcelain. No damage was detected on the glaze, and there was no change in existing cracks on the surface of the porcelain. The current evaluation results show that micronano bubble cleaning is safe for underwater porcelain, which provides important support for the application of this technology to the actual conservation of cultural relics.