The prevalence of emerging peer-to-peer (P2P) live broadcasting applications has practically demonstrated that they could scale to reliably support a large population of end users. However, these systems potentially suffer from two major threats: peers generally interact with unfamiliar partners without the benefit of trusted third party or verification authority, resulting in poor service if meeting with unreliable upstream nodes, while peers essentially tend to be selfish when it comes to the duty rather than the benefits and hence undermine the system performance. The trust and cooperation issues motivate us to investigate the design of trust-based incentive mechanism which establishes trustful relationship among peers and balances what they take from the system with what they contribute. The proposed TPOD mechanism leverages the statistical analysis to the practical service logs of client-server and P2P systems and effectively offers incentive through service differentiation. It goes beyond existing approaches in the following four desirable properties: (1)Trust-based; (2)Practical-oriented; (3)Objective metrics about past behaviors and (4)Distributed nature upon gossip-based overlay. The experiment results over PlanetLab verify its effectiveness.