The invention relates to a non-stretching straight-thread connection method of concrete beam reinforcing steel bars between two section steel columns. A weldable reinforcing steel bar connector is welded on either section steel column; longitudinal concrete beam reinforcing steel bars with straight-thread reinforcing steel bar thread heads at both ends are respectively connected with the section steel columns by the weldable reinforcing steel bar connectors; a separate sleeve tightly clamps the reinforcing steel bar thread heads of the two longitudinal concrete beam reinforcing steel bars to be connected, which are different from the reinforcing steel bar thread head at the other ends of the longitudinal concrete beam reinforcing steel bars connected with the weldable reinforcing steel bar connector; and the separate sleeve and the reinforcing steel bar thread heads of the longitudinal concrete beam reinforcing steel bars are pressed and tightly locked by two locking sleeves. The reinforcing steel bar thread heads do not need to rotate and stretch in the whole connecting process so that the non-stretching connection of the reinforcing steel bar thread heads is realized, and the connection mode is convenient to construct and can be widely applied to a construction part with both fixed ends and middle reinforcing steel bars needing mechanical connection.