In networked control systems, event-triggered control has been widespreadly used for its enormous advantages in the reduction of communication frequency and calculation time to save network resources and energy. However, this strategy was hardly extended to deal with uncertainty systems. In this paper, stability of observer-based event-triggered linear systems with parameter uncertainty is investigated. Sufficient stability condition is obtained in the form of linear matrix inequalities (LMIs), and meanwhile a minimum inter-event time (MIET) is derived to ensure feasibility. A numerical example is presented for illustration of the theoretical claims.