Based on low loss patterned ground shield interconnect transmission lines, we proposes a new structure of transmission line- slotted semi-coaxial line by using BCB and PI as the dielectric materials. We compared the attenuation constant and other properties of slotted semi-coaxial line and some different types of patterned ground shield slotted semi-coaxial line in single-ended with different slot widths. The proposed slotted semi-coaxial lines show lower attenuation constant by simulation under same spacing to side ground and same characteristic impedance.