Abstract: In the context of carbon peaking and carbon neutrality target, the energy system is facing tremendous pressure for low-carbon transition. As the largest source of carbon emissions and the key industry supporting electrification, the power sector plays a crucial role in the low-carbon transition of the overall energy system. In this paper, a long-term power system planning method with high spatio-temporal resolution and technical accuracy was proposed and a joint optimization model for long-term planning and short-term operation of the power sector was established. The low-carbon transition pathway of China's power sector was studied based on this model. Taking the carbon emission targets as constraints, the optimal scale, location and investment cost of different power generation technologies were determined. To achieve the climate targets, several key issues should be carefully addressed, including renewable energy expansion, premature retirement of coal plants, deployment of carbon capture technologies and guarantee of investment. By conducting detailed comparison and analysis of the pathways and costs under different emission targets, this paper provides scientific support for policy making.