Silicon carbide nanotubes (SiCNTs) have broad application prospects in the field of micro-nanodevices due to their excellent physical properties.Based on first-principles,the difference between optical properties of SiCNTs where C atom or Si atom is replaced by group-V element is studied.The results show that the optical absorptions of SiCNTs doped by different elements are significantly different in the band of 600 nm-1500 nm.The differences in photoconductivity,caused by different doping elements,are reflected mainly in the band above 620 nm,the difference in dielectric function and refractive index of SiCNTs are reflected mainly in the band above 500 nm.Further analysis shows that SiCNTs doped with different elements change their band structures,resulting in the differences among their optical properties.The calculation of formation energy shows that SiCNTs are more stable when group-V element replaces Si atom,except N atom.These research results will be beneficial to the applications of SiC nanomaterials in optoelectronic devices and provide a theoretical basis for selecting the SiCNTs' dopants.