In this project report i have implement the buck boast converter using matlab. in this paper matlab codes are also available ane with block diagram.DC-DC Converters are important components of hybrid automobile drive trains. They are necessary to change the DC voltage level and arrange it for each electrical component in the drive train.The buck–boost converter is a type of DC-to-DC converter that has an output voltage magnitude that is either greater than or less than the input voltage magnitude, hence it is named so. Two different topologies occur normally for buck–boost converter. Both of them can produce a range of output voltages, from an output voltage much larger (in absolute magnitude) than the input voltage, down to almost zero