Sarir field is the largest oil field in Libya. The Sarir field, which is 56 km long and 40 km wide , covers about 378 km2 of southern east part of Libyan Desert. Oil was discovered by the first well - C 001-65 on 15th December, 1961.The geological formation of this field is a complex composition of sandstones from the cretaceous period. Currently this field has about 350 wells , all of which are producing with electrical submersible pump. The purpose of this thesis is to analysis the current design and production optimization to perform ESP for five wells in this field. Production optimization was achieved by the Principles of Nodal Analysis Technique which was applied between the reservoir and the wellhead surface choke and ignoring the separator. SubPump and Avocet well surface modeler softwares were used to perform the calculations. Two approaches are considered in this study to optimize the production: Production of gas- lift optimization by combining as a secondary method with electrical submersible pump (ie, ESP / GL), and then Resizing and optimizing current design pump setting depth. Several benefits and advantages are achieved from applying those approaches, for instance , saving power, reducing number of stages and production improvement. Those approaches were evaluated based on economically net cash flow ( NCF) calculations for five years period . Moreover , comparing the NCF which was resulted from applying those approaches with the present status indicates higher improvement and good results. Applying the combination of ESP / GL method and optimizing the pump setting depth increase the NCF by 40% and 28 %, respectively relative to the present status. The two approaches when compared technically, advantages of higher production , lower power consumption and lower stages observed in the combination of ESP / GL. On the other hand, minimizing tubing and cable , in addition to production improvement observed in shifting the pump up and optimizing the pump setting depth.