The invention discloses a fermented barbecue sauce seasoning and a preparation method thereof. The preparation method comprises the following steps: inoculating a compound strain, and performing temperature-controlled fermentation to obtain soybean paste and flour paste respectively; then, with the soybean paste and the flour paste which are obtained through synergistic fermentation of multiple strains as main raw materials, supplemented by maillard reaction spice (meat flavor), chopped chilli, dried hot pepper powder, natural spice, vegetable oil, chicken oil and the like, stir-frying to obtain the fermented barbecue sauce seasoning. The fermented barbecue sauce seasoning has the effects of coloring, enhancing the aroma, removing the mutton smell, flavoring and the like. The fermented barbecue sauce seasoning skillfully utilizes amylase and protease (providing precursors for a maillard reaction) in the soybean paste and the flour sauce through the synergistic fermentation of the multiple strains, and nutrients and flavoring substances in the raw materials are fully released, so that the barbecue sauce flavor is outstanding; and in addition, the fermented barbecue sauce seasoning is especially suitable for smokeless barbecuing in an electric oven, can effectively solve the problem that barbecuing on a charcoal fire easily produces carcinogens, namely polycyclic aromatic hydrocarbons, and environment pollution, improves the barbecuing safety, is an environment-friendly barbecue sauce and can be stored for more than 6 months.