This study examines how changes in oil supply impact oil prices and China's macroeconomy. We developed an estimator that uses OPEC's institutional characteristics and high-frequency data to identify an oil supply surprise shock. This oil supply surprise is then incorporated as an exogenous variable into a TVP Proxy VAR model to analyze the effects of oil supply shocks on China's economy. Our findings indicate that negative oil supply shocks lead to higher oil prices, which in turn cause increases in China's interest rates and inflation, a decline in stock prices, a short-term rise in exports, and a long-term decrease in industrial output. When considering time-varying model parameters, we found that periods with larger oil supply shocks have a more pronounced impact on the macroeconomy. Our research provides empirical evidence for a better understanding of the effects of energy supply fluctuations.