Abstract: An analysis system for quick estimate of threedimensional ocean temperature, salinity, and current fields is developed. In the system, the average over the longtime ocean numerical model experiment results is taken as the climatology background. The available insitu measurements, satellite altimetry, and remotely sensed sea surface temperature are used to correct the background by the Ensemble Optimal Interpolation (EnOI) that may adjust multivariables. The adjusted climatology background fields are used to produce the instantaneous or present background. And then, the realtime or nearterm observations are assimilated to estimate the threedimensional ocean states via EnOI. The system does not require the integration of the ocean model. Therefore, it may quickly estimate the ocean state with less computational load. It is more suitable to the emergency and some situations where there are no powerful computational resources (for example fleet). In 2009, the system is applied in Gulf of Aden. The results show that the system with rapid estimates of present or nearterm ocean conditions has good performance.