Significant efforts have been made by China to support and promote the United Nations Sustainable Development Goals. Reducing energy intensity, improving overall energy efficiency and completing the green and low- carbon transition of energy are inherent requirements for China's energy sustainable development. This study focuses on the energy intensity in China. The analysis is conducted at three levels, namely, national, eight comprehensive economic zones and provincial levels. A time-series analysis of China's overall energy status from 2014 to 2023 is performed, along with the calculation of energy intensity for 30 provinces. Subsequently, the spatiotemporal differences of each province and the eight comprehensive economic zones are analysed. The sigma convergence model is employed to assess the characteristics of China's long-term changes in energy intensity. Finally, the spatial regression model is used to examine the influencing factors of energy intensity and the spatial spillovers. Results show the following. (1) At the national level, across the comprehensive economic zones and at the provincial level, energy intensity in China has shown a consistent decreasing trend, indicating continuous improvement in energy utilisation efficiency. Moreover, there are obvious regional heterogeneity and echelon stratification phenomena in energy intensity. (2) Among the eight comprehensive economic zones, the energy intensity differences between provinces in the three zones exhibit a narrowing gap. The other five zones show an increasing divergence in energy intensity across provinces. (3) Positive spatial spillovers of energy intensity are observed in provincial energy intensity, suggesting that provinces may imitate each other to form a beneficial competition or cooperation. (4) Economic development level (EDL) and industrial structure change (ISC) significantly and positively influence energy utilisation efficiency. Policy implications for industrial restructuring based on regional heterogeneity and establishing regions as role models for green and low-carbon transition with positive spatial spillovers are proposed.