This study aims to analyze the key determinants of public expenditure in Libya, relying on a theoretical framework that links it to fundamental macroeconomic variables, namely Gross Domestic Product (GDP), the inflation rate, and the exchange rate. The study employed a dual-method approach, combining both descriptive and econometric analysis. The descriptive analysis reviewed the evolution of public expenditure in the Libyan economy during a critical and volatile period (1990-2022), revealing that public expenditure was characterized by high volatility and was profoundly influenced by political transitions and internal conflicts. On the econometric front, an Autoregressive Distributed Lag (ARDL) model was constructed to quantitatively test these relationships, treating public expenditure as a function of GDP, inflation, and the exchange rate. The results indicated the existence of a long-run equilibrium relationship between public expenditure and its determinants, offering valuable insights for policymakers......................... Keywords: .................Public Expenditure, Gross Domestic Product (GDP), Inflation, Exchange Rate, Libyan Economy, ARDL Model.