Gene regulatory networks (GRNs) has highlighted the importance of gene regulation and these regulatory interactions form a complex network that can evolve over time. The evolution of GRNs can be explained in multiple perspectives. First, the structural change such as gene duplication and gene loss can change the topology of GRNs. Second, the comparison of the same GRNs in different species may explain the evolution of GRNs. Here, we consider how network topology affects the evolution of network states in response to fluctuations in the environment and whether topology itself is expected to evolve in a consistent way. Then, we examine a specific model, p53 pathway. p53 is the most frequently mutated gene in human cancer and it's has been studied well. From the evolutionary perspective, we decomposed the p53 pathway to several configurations which are derived from the phylogenetic tree of the p53 pathway. We prove the function of each feedback loop and show how the p53 pathway evolves. Lastly, we look narrowly into C. elegans p53 pathway, CEP -- 1 pathway. C. elegans has been studied as an useful genetic model for cellar response. We compare the structural and functional difference of p53 in C. elegans and mammalian.