The invention relates to an observation experiment system for flame propagation behavior of dust explosion. The observation experiment system comprises a pipe assembly, forming with an observation area; a dust supply device which supplies dust to the observation area; and an ignition mechanism fixed on the pipe assembly and used for igniting dust in the observation area. The dust supply device comprises a powder storage tank stored with dust; a nozzle connected with a powder storage tank; a heating mechanism used for heating the dust in the powder storage tank to the melting point to form a liquid fuel; and a first high-pressure gas storage tank provided with high pressure gas and communicated with the powder storage tank through a first pipeline. Wherein, the liquid fuel in the powder storage tank is sprayed into the observation area through the nozzle under the action of the high-pressure gas in the first high-pressure gas storage tank, and dust cloud with uniform granularity and regular shape is formed, the dust cloud is ignited by the ignition mechanism, so that the flame explosion behavior of dust explosion can be observed in the observation area.