Abstract: As a way to integrate various flexible loads into distribution network, prosumers have to be proved to be able to effectively improve the economy and reliability of the system. However, the flexibility of prosumers is uncertain in actual optimization. To cope with the uncertain flexibility of prosumers that existed in practical optimization of distribution network, a robust virtual battery model was proposed to describe the flexibility of prosumers, and the well-managed prosumers were applied to electricity and natural gas system, and an energy-reserve co-optimization model for multiple standby-resources in distributed multi energy system was put forward. Considering the reserve capacity provided by generating sets could hardly satisfy the dispatching requirements due to grid connection of large-scale wind power and the fault caused dispatching requirements, therefore a standby plan including generating sets, energy storage devices, interruptible loads and prosumers was designed, and under forecast errors and fault situations the restricted conditions of the transmittability for reserve capacity were considered. To protect the privacy of different energy systems, the proposed robust virtual battery model was solved by improved distributed alternating direction method of multipliers. A power and natural gas system consisting of 24-bus power system and 6-bus natural gas system was designed to verify the feasibility of the proposed model, especially to prove that high permeability of prosumers can effectively improve the system economy.