For seeking metal powder interference agent with optimal extinction performance in outer space, the relationship model between each components content in metal powder and extinction performance is established on the basis of Drude model. The extinction parameter Q_e/d of brass is calculated by Mie theory. Results show that when the zinc content in brass powder is lower, the extinction performance increases with the increasing of zinc content and the extinction performance is optimal when the zinc content reaches 42%. The experimental results demonstrate the rationality of the conclusion.