Helical drilling experiment of SiC ceramic was carried out by femtosecond laser. Effect of energy density on the processing morphology and shape of micro-hole in material was studied. The laws of variation of diameter, circularity and taper of micro-hole with laser machining parameters were analyzed. The experimental results showed that micro-hole at entrance was less affected by energy density in comparison with exit. Higher energy density was conducive to improve the processing quality of micro-hole. Near cylindrical micro-hole of SiC ceramic with diameter < 250 μm, circularity > 0.95 and taper < 1° was obtained in this study. It was found that a certain degree of oxidation existed on the surface of material by detecting the machining zone. Reasons for changes of elemental contents in different processing areas were analyzed.