Abstract: Integrating large-scale renewable energy such as wind power and photovoltaics (PV) into the power system is a key in realizing its low-carbon transition. Due to the volatility and uncertainty of renewable energy outputs, there are many studies to solve the huge challenges resulting from integrating large-scale renewable energy in the long-term planning of the power system. This paper first analyzes the main technical characteristics of the new power system. Then, the key challenges in terms of economic and policy uncertainty of energy supply, energy supply security brought about by the low-carbon transition with high penetration of variable energy are studied. The review shows the main challenges and current research results of the power system long-term planning, including long-term uncertainties, short-term uncertainties, evaluation of system stability and adequacy. The difficulties and potential research contents needed to be taken into consideration are revealed. Finally, future trends about the exploration and application of the power system long-term planning are summarized and prospected.