Abstract: With the development of modern radar technology, the spacing between slotted waveguide antenna elements is becoming smaller and smaller and the installation position accuracy of slotted waveguide element is getting higher and higher. It is difficult for the conventional structure to meet the new requirements of structure design of slotted waveguide antenna element, so a new structure is urgently needed to solve the above problems. A new structure is proposed in this paper according to the new requirements of the structure design of slotted waveguide antenna. The structure design of slotted waveguide, absorption load and coax-waveguide transformer is studied. In addition, the installation method, installation position accuracy and inner cavity protection of slotted waveguide antenna element are described in detail, which solves the problems of difficult installation and low position accuracy of slotted waveguide antenna. This new antenna has already applied to a dual polarization active phased array radar and good results are obtained, which verifies the rationality of the structure design.