1. Dispersion of faults: This is the biggest reason to introduce DCS system, the DCS system is to solve the fatal weakness of the centralized control system, the "concentration of faults". The reasons of dispersion of faults are that a lot of microprocessors are used in DCS system, each microprocessor undertakes the control task of small range (local) . The fault of a certain microprocessor will not affect the normal work of the whole system. 

2. Reducing the size of the control room or the length of the control dial. 

3. Largely reducing the cables required by the control system.

4. Largely reducing the varieties and quantities of the spare parts required by the control system.

5. Reducing the relying of the process operation on the instrument control equipment manufacturers in order to reduce the cost required by the training to the instrument control personnel. 

6. Providing the flexibility of composition of control system and having the convenient configuration and extensibility.

7.Realizing management to the process real-time parameters and historical data, providing function of performance calculation and equipment life calculation. This cannot be caught up by any traditional instrument control system .