Provided are a method and an arrangement for monitoring performance of a burner of a suspension smelting furnace. The burner is arranged at the top structure of a reaction shaft of the suspension smelting furnace. The burner has a solids feeding channel that has a solids outlet opening up into the reaction shaft, and a reaction gas channel comprising a reaction gas channel a that has a reaction gas outlet opening up into the reaction shaft. The arrangement comprises at least one imaging means for producing images representing the cross-section of the reaction gas channel, and a processing means for receiving images of the cross-section of the reaction gas channel from the imaging means.