In order to reduce carbon dioxide emissions, accelerate renewable consumption rates, and improve economic benefits, a multi-objective day-ahead scheduling model of connected multiple regional integrated energy systems considering energy sharing is developed in this paper. Physical and operation constraints of all equipment within the regional integrated energy systems (RIES) are first mathematically established. A multi-objective day-ahead scheduling model is then introduced to simultaneously achieve the minimum cost, the maximum renewable energy consumption rate, and the minimum carbon emissions goals while allowing energy sharing among regions. The developed scheduling method of RIESs with energy sharing is an effective way to achieve carbon peaking and carbon neutrality goals and overall benefits in the energy transition path. The developed model is verified through the modified IEEE 30-bus system, and the results show that considering the energy sharing, the power purchase from the grid is reduced, leading to the reduction of the dispatching cost. The PV curtailment rate and carbon emissions are also reduced when energy sharing is considered in view of the multi-objective optimization structure.