This study focuses on the formation,migration and dissipation mechanisms of the Sri Lanka Dome (SLD) and its combination with Bay of Bengal Dome (BBD) using Simple Ocean Data Assimilation reanalysis data and AVISO data.The SLD is a cyclonic eddy in the southwest Bay of Bengal,which occurs during May through September coinciding with the intrusion of southwest monsoon current into the Bay of Bengal.The results show that,Ekman pumping due to positive wind stress curl east off Sri Lanka is the governing mechanism of the SLD formation and migration during developing stage.Besides,a positive impact of cold Rossby waves propagation contribute to the SLD developing as well.Further,weakening positive wind stress curl and the eastern boundary reflected warm Rossby wave effect are important factors for dissipation of SLD.During the decaying stage of SLD,the BBD evolves independently because of the Ekman Pumping driven by local positive wind curl.The regression analysis proves that the local wind stress curl has a strong positive relationship with upwelling within the BBD.After September,weak positive wind stress curl dominates in the southwest BOB,the BBD starts to merge with the SLD.There are two kinds of links between SLD and BBD.The first is a dynamic interaction revealed by eddy kinetic energy analysis and the second is a thermodynamic interaction described by combination of subsurface cold cores of the SLD and the BBD.