Abstract: The cleanliness of X70 pipeline steel in the production process was investigated and assessed. In the meantime, the primary study and discussion of choosing and controlling the reasonable cleanliness for high-grade pipeline steel in its production were carried out too. The results show that the linear relationship be-tween the increased steel quality and its improved cleanliness does not exist. The steel cleanliness should not beexcessively pursued. It is more beneficial for reducing production cost and enhancing steel quality when the dis-tribution of inclusions is uniform, fine and dispersing when the reasonable steel cleanliness is attained.