Abstract: The main power station is the most significant part on offshore oil platform because of its vital function of power generating performance. Firstly, this paper briefly describes the main power station on offshore oil platforms in several aspects, such as set type, characteristics and working principle or concept, etc. Secondly, considering the characteristics of JZ 25-1S oil/gas field, analysis and calculation of electrical power consumption was carried out based on the relative data of the oil/gas filed, therefore the typical electrical power consumption and correlative data necessary for the design and selection of main power station was acquired. At last, the main power station plan of JZ 25-1S oil/gas field is chosen from reciprocating engine driven generator sets and gas turbine generator sets by comparing parameters, such as unit capability, load bearing capacity, standby rate, weight and platform space situation, etc. The design and selection process of main power station has been deeply discussed and detailed plan for JZ 25-1S oil field development project has been presented in this paper which provides a good reference for the design and selection of main power station on offshore oil platforms.