Luminescence properties of basal plane dislocations in 4H-SiC are studied by means of cathodoluminescence(CL) and defect selective etching. It is found that basal plane screw dislocations (BTSD) and basal plane mixed dislocations (BMD) have green and blue-green luminescence properties, respectively. The spectrum peaks near 530 nm and 480 nm correspond to BTSD and BMD,respectively. It is found from measurement that the luminescence peak from BMD is blue-shifted. The atoms of BTSD near the dislocation core are affected by tensile stress along the Burger’s vector direction, leading to its band gap narrowed. In addition, the Burger’s vector of BMD has both screw and edge components. It is the edge component that is responsible for the band gap broadening. In other words, the wavelength from BMD is shorter than that from BTSD.