This Letter, for the first time, proves that a general invariant velocity is originated from principle of special relativity, namely, discovers origin of the general invariant velocity. When the general invariant velocity is taken as light velocity in current theories, we get the corresponding special theory of relativity. Further, this Letter deduces triple special theories of relativity in cosmology, and cancels the invariant presumption of light velocity. When a kind of matter with the maximally invariant velocity that may be superluminal or equal to light velocity is determined by experiments, then utilizing this Letterʼs theory, all results of current physical theories are consistent.