Abstract: The development of radar technology makes higher requests for components. Microwave ferrite device is required to be miniaturized, planarized, thin filmed; wide frequency band, little insertion loss, high isolation; low cost and strong lot production capability. The microstrip microwave ferrite device is the first choice to meet these requirements, especially, the surface mounted microstrip device has significant advantages in integration and reliability compared with the traditional bonded devices. This paper describes a surface mounted microstrip isolator, using HFSS simulation software and VNA measurement techniques, a kind of surface mounted microstrip isolators in semi-open structure is successfully realized, the innovation of this paper is the isolator with two metallic welding pads on the back. Compared with the traditional ball planting technology for surface mounted isolators, the design reduces the special processes of assembling segment, ensures the coplanarity of the ports and the ground, declines the risk of deformation and oxidation for wave ports, simplifies the installation process for the customers. The isolator features two ports VSWR of ≤ 1. 20, insertion loss of ≤ 0. 4 dB for S21, isolation of ≥ 25 dB for S12, and it works at X-band.