Anti-sorting signal design is an important direction of Radio Frequency (RF) stealth signal design.It is based on anti-sorting signal design principle, which is essentially the failure principle of radar signal sorting algorithm.Clustering pre-sorting plays a key role in radar signal sorting, which has the advantages of fast sorting, simultaneous sorting of multiple emitters, and significant reduction in the computational burden of main sorting.However, in the field of RF stealth anti-sorting signal design, the study of a unified and widely applicable clustering sorting failure principle to guide the anti-sorting signal design has not been disclosed in formal literature.In this paper, by studying the principle of K-means clustering algorithm based on data field and fuzzy C-means clustering algorithm, and as for the step of data similarity measurement which must be carried out in clustering algorithms, a clustering sorting failure principle that can be widely used is proposed.It makes both clustering algorithms fail in sorting and guides the design of RF stealth anti-sorting signal.The formula derivation and signal simulation prove the correctness of the principle, which provides theoretical support for the design of RF stealth anti-sorting signal, and can improve the efficiency of RF stealth anti-sorting signal design.