This paper studied the effect of initial plane of focal spot in femtosecond laser drilling of inclined holes on SiC/SiC composite. A set of drilling experiments has been conducted on SiC/SiC specimen with 4 mm thickness and approximate 1.5 mm using beam concentric scanning mode. The effect of initial focal plane on entry size and hole taper have been analyzed. The results show that the entry size will be increased and hole taper will be decreased in case of initial focal plane is put at leading edge. This is because machining time was longer and greater volume material was removed, compared with a lower position of focal plane. For the drilling of inclined holes, the deposition of slag can be found at the lower edge of the entry because these slag is tend to be carried away from that area. In case of 45° inclined hole drilling, relatively large cracks can be found at the lower edge of the entry, this is because the exhaust intensity of the heat and slag is relatively high for large inclined hole machining. In addition, the taper angle of the two sides of the inclined hole is different with drilling angle. This study provides useful results for the future research of fs laser drilling of SiC/SiC.