Solar-light-driven carbon-based photocatalysts have been widely used for CO2 conversion reaction. In this work, silver iodide (AgI)-decorated 2D structure graphitic carbon nitride (GCN) composite was prepared using nitrogen-rich melamine precursor and the characterization results reveal that the mixture of hexagonal wurtzite and cubic phases of beta,gamma-AgI are incorporated on GCN surface. Consequently, the photoconversion of CO2 over AgI/GCN composite was tested under visible light irradiation in triethanolamine medium. The main products from CO2 conversion were methane, acetone and ethanol. Besides, the effects of metal AgI loading (0.5-1.5%), the amount of photocatalyst (1-4 g/L) and irradiation time for CO2 photoconversion were evaluated. Furthermore, the charge separation mechanism associated with the AgI/GCN composite for CO2 photoconversion was also discussed.