In this brief, the dynamic event-triggered bipartite consensus is explored for discrete-time multi-agent systems (MASs) under competitive network. Different from the existing works on dynamic event-triggered consensus of discrete-time MASs, observer based protocol is proposed by using the related output information. With the help of Lyapunov function method, some sufficient conditions are obtained and the control gains can be determined by solving discrete-time algebraic Riccati equations. Finally, a simulation example is presented to effectively verify the theoretical results.