Abstract: Studies the relationship between a manufacturer as the leader and retailers as followers. Recent market structure was explored and the results showed that the realization of retailing behavior is shifting from manufacturers to sellers. This new marketing trend is discussed in detail to explore that what is the optimum advertising effect and co-op strategy between manufacturers and sellers in Stackelberg/Nash equilibrium. The efficiency of co-op adverting is therefore found if a manufacturer and seller joint together to share the investment in logo/trademark and local and other cities' advertising expenses. An example is given to reveal what change the manufacturers shall take in advertising strategy with the change in marginal profit rates of both manufacturer and seller.