Formal methods are required for the automatic generation of codes to ensure that the code generated by the compiler can be applied to nuclear power instrument and control systems and thus minimize the errors introduced by the compiler during the compilation of synchronous data-flow languages. This study uses the theorem proving tool Coq to formally define the syntax, semantics, and translation algorithms involved in the translation phase of the master-node input structure of the synchronous data-flow language from Lustre to Clight and completes the formal proof of the translation algorithm. It is shown that this formalized compiler can generate credible target code that is consistent with the behavior of the source code, and meanwhile, the generated target code can well satisfy the implementation specifications of nuclear power instrument and control systems.