By using electron spin resonance （ESR）, the intrinsic defects in high-quality semi-insulating 4H-SiC prepared by low pressure chemistry vapor deposition （LPCVD） are investigated. In dark-field condition, the results show that the defects have the characteristics of VC and its complex compounds, while the absorption spectra are obviously asymmetry and have wider ESR half-width. The asymmetric chart and the wider ESR half-width are attributed to the higher testing temperature, non-homogeneous distribution of the defect concentration and the unsymmetrical crystal structure in 4H-SiC. The distributions of electrons have little effect on the ESR characteristic at the testing temperature of 110 K.