In the carbon-constrained background, the energy exchange of multiple park-level integrated energy systems (PIESs) in same regions can contribute to carbon reduction and economy improvement. However, it is challenging to design the reasonable carbon trading mechanism to manage total carbon emissions, and PIESs face the problems of interest conflicts and the uncertainties of renewable energy sources (RES) in the energy exchange process. To this end, a cooperative scheduling model for PIESs based on the ladder carbon trading mechanism in uncertain environment is proposed in this paper to promote the low-carbon scheduling and achieve benefits coordination among PIESs. Firstly, the dispatch framework of PIESs with the situation awareness technology is constructed to address uncertainties of RES, thus helping system mitigate uncertain risks. Then, the low-carbon scheduling model based on ladder carbon trading mechanism is established to better manage total carbon emissions of system. Furthermore, the energy exchange processes of multiple PIESs are modelled by introducing cooperative game theory, and Shapley value is utilized to avoid the interest conflict. Finally, case studies certify the effectiveness of the proposed model in promoting the realization of low-carbon target and improving the economic performance.