<p>The quality improvement and cost reduction in the steel production process by precise alloying were elaborated in the current work by taking the precise calcium treatment of pipeline steels as an example. A modified online guidance software for precise calcium treatment was developed based on the thermodynamics of inclusion modification by calcium treatment and a neural network model for calcium yield prediction and applied on the production of pipeline steels. Applying the online guidance software, a more stable calcium content and a smaller nitrogen pickup after calcium treatment could be obtained. In addition, based on experimental results, the hitting rate of inclusion composition after calcium treatment increased from 67 to 100%, and the quantity and size of inclusions in rolled plates significantly reduced. Moreover, steel properties especially the toughness in terms of impact energy were improved to a certain extent, achieving the quality improvement of steels. Meanwhile, by applying the precise calcium treatment, the cost of calcium wire usage was reduced by 16.6% taking into account all the experimental heats as a whole.</p>