Abstract: Human society is now in its third stage of energy transformation, with the goal of carbon neutrality and sustainable development, after the first two major energy transformation periods. China's energy development is facing complex situation and severe challenges under the new situation. We must accelerate the low-carbon energy transformation to achieve carbon neutrality, and firmly safeguard the bottom line of energy security at the same time. It is a major issue for China's high-quality energy development to balance energy transformation and energy security. Studies indicate that: 1) the previous two energy transformations were both in line with the traditional law of economic development and accompanied by the industrial revolution. In these two transformations, energy acted as common productive factors, and the energy structure gradually changed under the drive of technology. However, the core reasons of the third energy transformation are to address climate change and guarantee energy security. The ongoing transformation is driven by the strategic measures of sustainable development besides technological development, and it requires multiple efforts. 2) there are lots of risks in China's energy transformation: the total energy consumption is too large, the carbon emission and proportion of coal in energy structure is too high, the domestic production of oil and gas is too low, the dependence ration of overseas oil and gas is too high, and the development of renewable energy is too weak. 3) under the goal of carbon neutrality, China's energy transformation and energy security should focus on "three acceleration": making full use of the advantages of socialist system, speeding up the construction of new energy system through the way of cleaning fossil energy, scaling up renewable energy and developing smart comprehensive energy, speeding up independent innovation of science and technology in the fields of coal, oil, gas and renewable energy, speeding up the implementation of energy conservation.

Key words: carbon neutral, energy transformation, energy security, coal, oil and gas, renewable energy, scientific and technological innovation, new energy system, energy independence