In order to solve the impacts of source-load uncertainty and multi-energy complex coupling on the optimal scheduling of a new building integrated energy system, and to realize the system economy and environmental protection, a low-carbon planning for buildings considering multi-objective CVaR and stepped carbon rewards and penalties under source-load uncertainty is proposed. First, the conditional value-at-risk theory is used to introduce the multi-objective CVaR method, and the multi-objective dispatch function with confidence level is redefined by taking the uncertainty deviation of new energy output on the source side as a stochastic variable; second, the stepped carbon reward and punishment model is constructed to measure the carbon emission of buildings, and the electricity, heat and cooling loads under complex energy coupling are flexibly modeled to achieve the collaborative optimization of the multi-energy streams complementing each other under the uncertainty of the source loads; and then, the energy energy quality coefficient model is established to ensure the energy efficiency of the system; finally, the economy and low-carbon environmental protection of this model are verified by example simulation.