Abstract: For air-borne, satellite-borne and ship-borne phased array radars, the microwave modules with small size , lightweight, high performance and high reliability are needed because of their special environment. LTCC substrate with the properties of high density, embedded R/L/C and chips has become an ideal high density substrate for microwave modules. In this paper the manufacturing technology of LTCC substrate with cavity is introduced, the key manufacturing processes of microstrip line , stripline, embedded R and cavity are analysedt and the relevant solutions are suggested.