With increasingly complex tasks, cooperation among multiple unmanned aerial vehicle (UAV) groups has become more significant. However, in complex operational environments, UAVs may operate outside the communication coverage of the trusted authority (TA), making continuous online TA services unavailable. Under such circumstances, most existing group management methods have difficulty achieving group fusion and cannot flexibly update post-fusion member certificates. Therefore, we propose an autonomous UAV group management scheme based on mobile proactive secret sharing. First, the scheme achieves autonomous group fusion by updating the subsecrets of UAVs. Second, without the participation of a TA, the scheme supports the dynamic self-updating of certificates, ensuring secure communication in the new group and continuous availability of certificates. Security proofs and analyses show that the proposed scheme is secure under the random oracle model and can resist several common attacks. The experimental results demonstrate that the proposed scheme outperforms related schemes in computational performance and is suitable for secure and efficient UAV group management scenarios.