This paper reports the CTFBG with the ability to support the highest power laser at home and abroad. The CTFBG on 25 μm/400 μm fiber supports the more than 4 kW laser power with an insertion loss of less than 0.3 dB and a high thermal handling capacity (~1.72 ℃/kW). It is of great significance to promote the development of domestic high-power CTFBGs and expand their applications in high power fiber laser systems.