A sodium borosilicate controlled-release inhibitor has been prepared via calcination for suppressing carbon steel corrosion in simulated recirculating cooling water (SRCW). The synthesized inhibitor was mainly composed of B2O3 and SiO2, coupling with small quantities of NaB5O6(OH)(4)3H(2)O and NaB(5)O(8)5H(2)O crystals. The total boron concentration gradually increased to 250 mg L-1 during the 28 days of release (2 g inhibitor in 500 mL SRCW) at 50 C. A higher controlled-released rate existed in acidic environments (pH 5) than in neutral environments (pH 7) and alkaline environments (pH 9). The potentiodynamic polarization and electrochemical impedance spectroscopy results indicated that the inhibitor showed a better anticorrosion performance in neutral and alkaline environments than in acidic environments. In addition, a passive film with a Fe-O-B structure formed on the carbon steel surface to prevent the attack of the corrosive ions. A passivation-pitting-repassivation process was detected in the passive film by electrochemical noise, which demonstrated that the passive film exhibited a self-healing capacity. Moreover, a potential corrosion risk under the film was detected under the passive film in alkaline environment after 21 days of immersion. According to the experiment results and the analysis results of the point defect model, we believed that the anticorrosion performance of the sodium borosilicate inhibitor was in the following order: pH 7 > pH 9 > pH 5.