Regulating valves are the important components of control system on oil pipeline. The opening of the valves is changed to regulate flow and pressures of pipelines. Operating characteristic of valves is the most important factor influencing the regulating quality, and the distortion is great in actual operation with the variation of working conditions. Beginning with the inherent flow and resistance characteristics of regulating valves, the coefficient of discharge was adjusted considering the influence of fluid viscosity. The relationship between the deformity characteristics of valves and ratio of pressure cut down or turndown ratio was discussed. The system made up by a pump, a valve and a tank was an example to analyze the factors affected the operating characteristic of valves in the actual operation. The influences of different closing valve times, different closing valve laws and different ratio of pressure cut down or turndown ratio on the operating characteristic of valves were analyzed by simulation using Visual Basic program. The results indicated that the operating characteristics of valves were different. And the method of two-stage closing valve was adopted according to the changes of operating characteristic of valves by different closing valve time, different shutting valve laws. The distortion degree of valves in the operation of pipeline was decreased mostly. Then the selection measures of regulating valves were discussed. The factors influencing operating characteristic of valves were analyzed comprehensively. Theory criteria can be provided for selecting regulating valves of pipeline correctly. It is also the key to stable and economically operation control of pipelines.

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