Synchronous data-flow languages, such as Lustre and Signal, have been widely used in safety-critical industrial areas, such as airplane, high-speed railways, nuclear power plants, and so on, for example, Scade, a tool suitable for modeling and developing a real-time control systems in those areas, is based on a Lustre-like language. Naturally, the safety of development tools, especially compilers, for such languages, has been paid highly attentions. In recent years, the construction of a trustworthy compiler based on formal verification has become one of the research focuses in the field of programming language, and remarkable achievements have also been achieved, for example, a product level trustworthy C compiler has been developed in the CompCert project. Similarly, this method has been used to develop the trustworthy compilers of a synchronous data flow language. Two long term projects for such research work, called Vélus and L2C respectively in this study, are focused here. Either of them has been developing a compiler for a Lustre-like synchronous data-flow language. The analysis and comparison are deeply carried out in terms of various points between Vélus and L2C.