Air Pollution is a major concern in our country due to which Indian Government has taken a decision to move from BS-IV to BS-VI which is nearly 90% reduction in NOx and 50% in particulate matter along with addition of particulate number regulation for BS-VI in comparison to BS-IV norms in very short span of time. Vehicle manufacturers are also having the challenge to produce low cost and fuel efficient product with BS-VI solution in order to meet tightening emission regulations and increasing needs of lower fuel consumption. Detailed study is done with different approaches to meet BS-VI emission which is elaborately explained in different aspect of engine design and after treatment parameter with its pros and cons. After Treatment selection plays an important role in engine development to meet stringent emission legislations and customer demands. Strategies for BS-VI were described with the advantage and drawbacks for after treatment selection. The cost of after treatment and its durability is also the major challenge to establish the BS-VI solution in the market. The injection pressure and turbo charger also play the vital role for strategic decision from the base engine side. Comparative study is done with different aspects of after treatment and base engine design aggregates to meet the emission for BS-VI. Keywords: After treatment, NOx, BS-VI norms etc.