Abstract: In response to the engineering requirements of high-density integration, miniaturization, and lightweight of T/R modules in active phased array systems, a four channel high-density hybrid integrated Ku band T/R module based on SiP packaging has been developed on the basis of breaking through the traditional Brick-type structure of T/R modules and the stacked structure of tile-type T/R modules. The external interface of this T/R module uses BGA ball grid array to replace conventional SMP connectors for signal interconnection, resulting in lower cost, smaller volume, more compact structure, and lower profile height, The BGA ball is directly connected to the external circuit through welding, reducing the application of RF and low-frequency cables, making the interconnection more free and convenient for the cable free, reconfigurable, and multifunctional design of radar systems. In the design process of this component, a stability design method for T/R module in a narrow and high-density integrated environment is proposed by referencing the idea of transfer functions in control theory. This method effectively solves the instability problem caused by multiple physical fields and other factors in T/R modules in high-density integrated environments. The principle design, circuit design, and low loss transmission interconnection design of the T/R module are detailed in the article. According to the antenna unit layout requirements, the structural size of the module is 13.5 mm×15.0 mm× 2.8 mm (including the height of BGA solder ball), processed and tested on the actual component. The assembly process of the component is reliable, has good manufacturability, and has good consistency in amplitude equality indicators, which can meet the engineering application of phased array radar.