The present paper is concerned with the stabilization of a one-dimensional Korteweg-de Vries (K-dV) equation with boundary control and observation. The boundary observation suffers from an arbitrary given time delay. First, by using the spectrum analysis, it is shown that the proportional output feedback control that stabilizes exponentially the time delay free system cannot stabilize the corresponding time delay system anymore. Then by using the observer and predictor developed by Baozhu Guo, we solve the stabilization problem of time delay system: the state is estimated in the time span where the observation is available; and the state is predicted in the time interval when the observation is not available. It is shown that the estimated state feedback stabilizes exponentially the time delay system.