Amyotrophic lateral sclerosis (ALS) is a blurred and indistinct concept and definition, didn't properly update since the first description, which is far from being suitable for the current implementation of clinical and scientific research present and need urgent solution. Furthermore, the current diagnostic criteria need also further improve because the diagnostic measures have majorly depended on clinical manifestations yet up to now, which isn't conducive to early diagnosis and prolong the exact diagnosis. In this mini review, we firstly discuss the doubt about the concept and definition of ALS, and then review the question of recent diagnostic criteria, in order to further understand the concept, definition and diagnosis of ALS.