Abstract: A mill cutter assembly comprises a handle having a tapered hole and a through hole; an upper end of an connecting block having a threaded hole; a lower bottom of the connecting block being formed with an engaging groove; a knife having a lower portion and the lower portion being formed with a helical trench and a helical cutting portion; an upper end of the knife being formed as an engaging section which can be inserted into the tapered hole of the handle; an outer side of the engaging section having a tapered shape; an upper side of the engaging section being formed with an engaging block which is engagable with the engaging groove of the connecting block; and a stud having a head and a shaft extended downwards from a lower side of the head; the stud having a straight rod and a threaded rod.