The establishment of nationwide carbon market has become one of the important means to combat climate change in China. Given the diversity of resource endowments and spatial heterogeneity of economic development across different regions,there is great uncertainty about the impacts of a nationwide carbon market on regional economies. This paper develops a multi-regional CGE model, which is in combination with an emissions trading model,to simulate and assess the impacts of a nationwide carbon market on the coordinated development of regional economies. Six emissions trading (ET) scenarios are designed according to different initial quota allocation mechanisms,including three allocation criteria of Historic Emission,Ability to Pay,Twelfth Five Year Plan,and two allocation methods of free allocation and hybrid allocationfree allocation with energy sectors while auction with energy-intensive sectors. The results show that national GDP and welfare increase by 0.027% - 0.056% and 32.373 - 50.756 billion yuan under ET scenarios,respectively,as compared with the non-emissions trading (NET) scenarios. It indicates that a nationwide carbon market can effectively reduce macroeconomic costs for the whole society,improving regional welfare and reducing regional economic disparities. Industry output also decreases in a smaller range under ET scenarios,as total output increases 0.335% - 0.473% compared with NET scenarios. It is more significant in the electric power industry output,the decline of which is only 1.829% - 1.895% under ET scenarios while it is almost 6.079% - 6.440% under NET scenarios. At the same time,a large-scale trading funds of about 458.02 -3 925.09 million yuan is transferred from eastern region to central and western regions under the nationwide carbon market,of which the resource regions have an inflow of 397.20 - 1 741.90 million yuan. These trading funds can be further used by resource regions to invest in CO_2 mitigation technologies. Additionally,the impacts of a nationwide carbon market are closely related to the initial quota allocation mechanism. Eastern regions benefit more from the establishment of nationwide carbon market under the Ability to Pay criterion,nevertheless,central and western regions benefit more under the Historic Emission and Twelfth Five Year Plan criteria. The comparison of free allocation and auction shows that a hybrid allocation method of free allocation and auction is preferable in the preliminary stage of a nationwide carbon market in China.