This paper investigates privacy-preserving bipartite consensus for second-order multi-agent systems over cooperative-competitive directed signed networks. To prevent the leakage of agents’ state information during communication, a position-based privacy-preserving control protocol is developed via state decomposition. Specifically, the true state of each agent is decomposed into coupled substates, so that the transmitted position information does not reveal the complete private state. By exploiting structural balance and gauge transformation, the signed interaction topology is converted into an equivalent nonnegative network. A distributed sampled-data protocol is then constructed, and a necessary and sufficient condition for bipartite consensus is established. It is shown that the proposed protocol guarantees bipartite consensus while preserving state privacy against honest-but-curious and external eavesdroppers. Numerical simulations are finally provided to illustrate the effectiveness of the theoretical results。