The utility model provides a system for a controlling converter steelmaking process, and the system is used for solving the problems that the control effect of existing control devices is influenced by descending of a converter draught hood and accumulated slag of a fire door and the control accuracy is bad. The system comprises a furnace gas analyzing system, an oxygen lance control system and an industrial control computer. The furnace gas analyzing system is used for detecting concentration of components in furnace gas and furnace gas flow. The oxygen lance control system is used for controlling oxygen blast of a converter so as to obtain oxygen blast amount of the converter. The industrial computer is connected with the furnace gas analyzing system and the oxygen lance control system and used for calculating decarbonizing oxygen efficiency of the converter and decarbonizing oxygen efficiency change rate of the converter according to the concentration, the furnace gas flow and the converter oxygen blast amount of the components in the furnace gas and outputting splashing forecasting information or drying forecasting information. By means of the system, instability of manual experience control is eliminated. Compared with existing sonar slugging monitoring methods, the system is free of influence from descending of the converter draught hood and the accumulated slag of the fire door, controls accurately and improves stability of a smelting process.