In this work, 4HSiC epilayers were performed on 4°offaxis Siface substrates by horizontal hot wall chemical vapor deposition (CVD) with a standard chemistry of silanepropanehydrogen. A new type of triangular defect with inverted pyramid located at its apex(IPRTD) was observed. The morphology, microstructure and formation mechanism of the triangular defect were investigated by Nomarski optical microscope, laser scanning confocal microscope and microRaman spectroscopy. Characterization results indicates that the triangular defect observed has a 3CSiC nature. Based on these observations and analysis, a model of the formation mechanism of the triangular defect was proposed. In this model, the origination of IPRTD is attributed to 2D nucleation caused by dislocation located on the upstream of the growth direction. The difference in the growth rates between the stepflow growth direction of ［112-0］ and lateral growth along with the directions of ［11-00］/［1-100］ as well as the etching of the epitaxial layer by hydrogen are the main reasons for the formation of the inverted pyramid structure at the top of the defect.