The Continuous Stirred Tank Reactor CSTR is widely used in the chemical industry. The Cn - concentration - input chemical materials are continually loaded into the tank and this reaction process occurs making the output product have concentration Cn, which is continually taken so this process is highly productive. In aspects of control, the CSTR is nonlinear and coupling so the limited PID controller makes the quality of output products worsen, leading to accept the reduction of productivity of tank. To overcome this disadvantage, the researchers applied the nonlinear control law and designed a nonlinear control for the reactor process. In this paper, the authors will use the Nonlinear Passive Base Control method to control the Continuous Stirred Tank Reactor CSTR.