Abstract: To meet the needs of stealth, the enclosed masts with composite and steel materials are gradually applied on warships. The modal test of enclosed masts with composite and steel was done in this paper. Through the tes t, the numerical mast model was verified, and the influence law of composite sandwich plate thickness to vibration characteristics of mast and its top radar dome was under research by numerical method. The results show that the composite sandwich plate is in good condition in terms of vibration. Moreover, the prediction method of radar dome＇s general and local vibration frequency was extracted through the numerical results of octag gon mast in this paper. And through the test of tetragonal and hexagonal masts, the prediction method was proved to be universal. This paper aims to provide some favorable references to the structure design of enclosed complex integrated masts.