Abstract: At present, the Qing (Qinghai)-Yu(Henan) UHV DC Project for all-clean energy transmission has been put into operation, but the supporting power sources have not been fully put into production yet. Due to the big output difference of hydropower between flood and dry seasons, and the stochastic, intermittent and fluctuating characteristics of wind and photovoltaic power output, it is hard to meet the requirements for large-power and stable transmission of Qing-Yu UHV DC Project by Qinghai Grid alone. Based on an investigation of the load and generation characteristics of the sending-end Qinghai Grid, a power balance analysis is carried out for the outbound transmission of the Qing-Yu DC Project. Aiming at the problems of surplus in peak time while shortage in valley time, and rich in flood season while poor in dry season for power output in the Qinghai Grid, the paper proposes a bundled clean energy transaction model for multiple provinces in the northwest region, so as to give a full play of the overall dispatching role of the Northwest Power Grid. Simulations are carried out under four scenarios, including the new energy enrichment and barren periods, the flood season and the dry season of the Yellow River. The results show that the bundled transaction of clean energy can significantly improve the stable outbound transmission level of the Qing-Yu UHV DC Project.