Unmanned aerial vehicles (UAVs) have found enor-mous applications and are expected to bring tremendous op-portunities in the forthcoming 5G/6G wireless communications. However, there exist some challenges that need to be tackled for achieving reliable communications in UAV networks due to the open channels. In this work, we propose to perform a UAV-enabled virtual antenna array (UVAA) and adopt collaborative beamforming (CB) to transmit data towards different base stations (BSs), while an aerial user (AU) that locates near the UVAA is carrying out another task. In the considered scenario, we formulate a reliable communication multi-objective optimization problem (RCMOP) to simultaneously maximize the total receiving signal-to-noise ratio (SNR) of the BSs, minimize the total receiving SNR of the AU and minimize the flying energy consumptions of UAVs, which is achieved by cooperatively optimizing the positions and excitation current weights of UAVs and the order of transmitting data towards different BSs. The formulated RCMOP is sophisticated so that we propose an improved multi-objective salp swarm algorithm (IMSSA) to solve the problem. Simulation results verify that the proposed IMSSA can effectively solve the formulated RCMOP and it outperforms some other traditional strategies,