Aiming at the problem of formation control of micro-nano satellites with limited communication capability and input saturation, a distributed low gain micro-nano satellite orbital cooperative control strategy with collision avoidance capability based on event triggering mechanism is proposed in this paper. Firstly, an event triggering mechanism is introduced to replace periodic sampling communication to effectively reduce the controller update frequency. Meanwhile, a Luenberger state observer is used to reduce the error caused by the event triggering mechanism. Secondly, the artificial potential function is designed based on the distance between the individual satellite and the observable external obstacle, and the collision avoidance between the satellites and the external obstacle is realized. In addition, by solving the low gain parameter Riccati equation, a low gain formation control strategy was designed to solve the problem of control input saturation during the formation process. The consensus of the multi-agent system is proofed based on Lyapunov stability theory, which ensures achieving the time-varying formation configuration of micro-nano satellite cluster and avoids Zeno behavior. Finally, the simulations indicate that the cooperative control strategy proposed in this paper can effectively complete the formation task of distributed micro-nano satellites without collisions and reduce the update frequency of controllers during the formation process.