Increase in energy demands, stringent emission norms and depletion of oil resources have led the researchers to find alternative fuels for internal combustion engines. As petroleum is non renewable source of energy and the petroleum reserves are scarce nowadays, there is a need to search for alternative fuels for automobiles. The intensive search on alternative fuels for compression ignition engines has focused attention on fuels, which can be derived from bio mass. On the other hand waste plastic pose a very serious environment challenge because of their disposal problems all over the world. Plastics have now become indispensable materials in the modern world and application in the industrial field is continually increasing. An intricate detail about Pyrolysis has been discussed vividly to obtain plastic oil, which has been experimented to check the feasibility as an alternate fuel for Diesel engines.