Converters for Telecom dc/dc power supply applications often require output voltage somewhere within a wide range of input voltage. while the design of traditonal converters will come with a heavy penalty in terms of component stresses and losses and with the restrictions on output voltages. also the high efficiency around nomial input voltage is another restrictions on traditional converters. in this paper, to tackle these problems a controlling scheme for Four Switch Buck Boost Converters is designed by two methods , closed loop control using Genetic Algorithm and open loop control . hence GA is used to optimize the PI controller which is a feed back for closed loop control system.