The purpose is to produce a model of nuclear reactor trip logic caused by the steam generator water level of Wolsong 2/3/4 unit through an activity chart and a statechart and to produce C language automatically using Statechart-based Formalism and Stalemate MAGNUM toolset suggested by David Harel Formalism. It was worth attempting auto-generation of C language though we manually made Software Requirement Specification(SRS) for safety-critical software using statechart-based formalism. Most of the phases of the software life-cycle except the software requirement specification of an analysis phase were generated automatically by Computer Aided Software Engineering (CASE) tools. It was verified that automatically produced C language has high productivity, portability, and quality through the simulation.