Most chemical plant in China still use the manual work to sample and titrate in acid dip. However, this method, owing to its heavy factitious influence, has bad checking repetitiveness, real time, and unreliable which seriously influences the quality of acid dip. This affects the quality of product. For solving this problem, the paper proposes multi channel real time monitor system, using S7 200 PLC, Visual Basic and SQL Server 2000. The system has high flexibility and reliability, is convenient to extend and can display data visually and vividly. Furthermore, the system can use SQL Server to save historical data, which makes it easy to inquire and analyze data. Practical application of this system shows that it has good effect.