Disclosed is a crystal form of (6S)-5- methyltetrahydrofolate salt and a method for preparing same. The crystal form is: C form of the crystal form of (6S)-5- methyltetrahydrofolate calcium salt, the X-ray diffraction pattern thereof having diffraction peaks at the 2? angles of 6.3±0.2 and 19.2±0.2； or the crystal form of (6S)-5- methyltetrahydrofolate strontium salt, the X-ray diffraction pattern thereof having diffraction peaks at the 2? angles of 6.5±0.2 and 22.0±0.2. The crystal form of (6S)-5- methyltetrahydrofolate salt in the present invention has advantages such as excellent physicochemical properties, good stability, high purity, good reproducibility, and being more suitable for production on an industrial scale.
