The Statistics are indicated flare of 40 percentage of Associated Petroleum (APG) in iran that in this volum, iran have fourth rank in world and first rank in Middle East. Economic and enviomental dimensions of flare of this gased has led to in country is planned projects for gathering APG. In between these projects, NGL Unit has the main share in gathering of APG that in this between, NGL-3200 Unit, with capacity of 14.15 million cubic meters in day, is important due to gathering of APG from oil fields of karon West. Therefore, in present research, using Cost-Benefit Analysis method and financial index of Net Present Value (NPV), Internal Return Rate (IRR) and payback period is evaluated NGL-3200 project. The result of economic evaluation demonastrate that if this unit is acted with 100 percentage of capacity, then NGL-3200 project will have economic feasibility in IRR 28.29 percentage. Also, the result of sensivity analysis of project illustrate that first if feedof this unit have decrease excess 22 percentage, then this project don’t will have economic feasibility, second in the event of review NGL-3200, if nominal capacity of this unit have decrease excess 40 percentage, then will be lost economic feasibility of NGL-3200 project. Thirdly for given IRR 25 percentage, APG price should be 5.1 cent in current nominal capacity and 3.24 cent in nominal capacity Equivalent to 50 percentage of current capacity.