The present disclosure provides a method and system for gas leakage safety warning based on Internet of Things (IoT) of smart gas. The method is implemented by a smart gas safety management platform of an IoT system for gas leakage safety warning. The method comprises obtaining gas data. The gas data at least includes gas operation data and gas concentration data. The method also includes determining a gas determination scenario through a preset determination algorithm based on the gas data, and determining a dynamic threshold set based on the gas data and the gas determination scenario. The dynamic threshold set includes a dynamic threshold of a gas concentration change of at least one time point. The method further includes determining gas leakage warning information of the at least one time point based on the gas data, the gas determination scenario, and the dynamic threshold set.