A spring-forming control system and its control method for a spring forming machine in which the spring-forming control system uses a host computer to provide graphical spring parameter setting, program modification, and dragline-method program modification graphical interfaces that are selectively switchable on a display monitor. After setting of spring processing parameters through the spring parameter setting interface, a trial production is done subject to a spring parameter auto-generation software built in the spring-forming control system, and then the production is started if the trial meets the requirements, or the spring processing parameters are modified through the spring parameter setting interface, program modification interface, or dragline-method program modification interface if the trial does not meet the requirements, and then a further trial production is performed till the shaped spring meets the requirements. A spring preview is available during running of the spring-forming control system. The graphic interface operation has the advantages of convenience, rapidness, and accuracy.