We plan to choose the Fatty acid metabolic pathway for our system's application. We combine three key enzymes in Fatty acid metabolic pathway with our light controlled system. They are TesA, FabI and FabZ which affect three very pivotal reaction process. We expect that we can regulate the proportion of three enzymes by three different light-dCas9 systems to control the productive rate of fatty acid. We use the modeling tools to simulate the regulate process to verification our plan.