<p>In this paper, the authors explore the long-run energy efficiency determinants in the agricultural and industrial operation of China between the year 2005 and 2024. The Energy Efficiency Indexes (EEI) by sector are calculated by dividing the productivity by the sectoral energy use, and thus it creates the possibility to compare the efficiency across sectors. The four determinants analyzed are sectoral value added, urbanization, energy ratio (fossil fuels energy consumption to renewable energy consumption) and regulatory quality. The presence of I(0) and I(1) variables in stationarity tests is found mixed and hence reasons to use Fully Modified Least Squares (FMOLS) estimation to avoid losing the equilibrium information, and at the same time allow long-run relationships to be captured. Empirical findings reveal that energy efficiency generally improves substantially with increase in sectoral value addition both in the agriculture and the industry and that urbanization is positively related to increase in energy intensity with industry being the main contributor. Energy ratio is negatively correlated to EEI in both sectors indicating that the present fossil based energy system is relatively efficient at least compared to environmental targets. Although it has a negative sign, regulatory quality is insignificant in both models. Hansen Parameter Instability test demonstrates that cointegrating relationships are not unstable with time and therefore there might be a structural change of the determinants of energy efficiency. The results point to the necessity of sectoral policy interventions: a focus on technological upgrading and clean production in the industry, renewable-compatible mechanization in the agricultural sector, energy efficiency integrated into city planning, and enhanced sector specific regulations.</p>