A composite crossarm, arranged to be fixed on a pole body of a transmission pole, and the composite crossarm comprising: a core rod and; an insulating layer; wherein the insulating layer covers and is fixed to an outer peripheral surface of the core rod, the insulating layer being positioned in regions of the core rod other than a middle region of the core rod arranged to be connected to the pole body, characterised in that the composite cross-arm further comprises a load-bearing member, wherein the load-bearing member covers and is fixed to an outer peripheral surface of the core rod (101, the load bearing member being positioned in the middle region, wherein the insulating layer is sealingly connected to the load-bearing member, wherein the load-bearing member is a sleeve, and the sleeve has an inner wall with a shape corresponding to a cross section of the core rod covered by the sleeve, wherein the composite crossarm is arranged to be fixed on the pole body by the sleeve and a fixing device, wherein the fixing device comprises a crossarm receiving member and a pole body connecting member, the crossarm receiving member is used for receiving the sleeve, and the pole body connecting member is used for connecting the pole body and the crossarm receiving member, wherein the crossarm receiving member comprises a crossarm hoop and a connecting plate, the pole body connecting member is a pole body hoop, and the connecting plate is provided with a first mounting member cooperated with the crossarm hoop, and a second mounting member cooperated with the pole body hoop, and wherein the crossarm hoop is disposed to partly surround the sleeve along a circumferential direction of the sleeve and is fixed on the connecting plate by the first mounting member, and the pole body hoop is disposed to partly surround the pole body along a circumferential direction of the pole body and is fixed on the connecting plate by the second mounting member. a core rod and; an insulating layer; wherein the insulating layer covers and is fixed to an outer peripheral surface of the core rod, the insulating layer being positioned in regions of the core rod other than a middle region of the core rod arranged to be connected to the pole body, characterised in that the composite cross-arm further comprises a load-bearing member, wherein the load-bearing member covers and is fixed to an outer peripheral surface of the core rod (101, the load bearing member being positioned in the middle region, wherein the insulating layer is sealingly connected to the load-bearing member, wherein the load-bearing member is a sleeve, and the sleeve has an inner wall with a shape corresponding to a cross section of the core rod covered by the sleeve, wherein the composite crossarm is arranged to be fixed on the pole body by the sleeve and a fixing device, wherein the fixing device comprises a crossarm receiving member and a pole body connecting member, the crossarm receiving member is used for receiving the sleeve, and the pole body connecting member is used for connecting the pole body and the crossarm receiving member, wherein the crossarm receiving member comprises a crossarm hoop and a connecting plate, the pole body connecting member is a pole body hoop, and the connecting plate is provided with a first mounting member cooperated with the crossarm hoop, and a second mounting member cooperated with the pole body hoop, and wherein the crossarm hoop is disposed to partly surround the sleeve along a circumferential direction of the sleeve and is fixed on the connecting plate by the first mounting member, and the pole body hoop is disposed to partly surround the pole body along a circumferential direction of the pole body and is fixed on the connecting plate by the second mounting member.