Abstarct: Among nanomaterials, nanotubes and especially SiC nanotubes have various functions in Nano electronic devices due to their electrical, optical, thermal properties and high mechanical resistance; they are also compatible with microelectronic silicon due to stability and feasibility in energy gap. In this study, we have used density function theory (DFT) to GGA generalized gradient by SIESTA code in order to examine structural and electronic properties of pure double-walled SiC nanotubes including armchair (4,4) ¬@ (n,n) (n=6-14) and (5,5) @ (n,n) (n=7-15) and zigzag (5,0) @ (n,0) (n=10-17) and (6,0) @ (n,n) (n=11-18) and also doped with boron (B). The results show that the most desired inter-wall space for stability of armchair and zigzag nanotubes are3.6 and 3.5 Ǻ, respectively. Studying the band structure shows that all pure armchair nanotubes are semiconductor with indirect gap, so that the band gap will increase by diameter like single-walled nanotubes. In zigzag, (5,0) @ (n,0) is conductor and (6,0) @ (n,0) is semiconductor with direct gap that will increase with diameter. The calculations indicate the lower gap for double-walled against single-walled nanotubes, and the gap variation in armchair samples is more than zigzag ones. The results acquired from doping of double-walled armchair zigzag nanotubes indicating their inter-wall space variations compared to special case and decreasing energy gap to zero and finally conductivity of doped nanotubes. The results of this study could be proper candidates for designing Nano-scaled devices such as small sensors, fuel cells, transistors, Nano-tools, molecular computers and other Nano electronic instruments.