The invention provides a tank type circulation fermentation preparation method of broad bean sauce. The method comprises the following steps: A, pre-treating broad beans; B, preparing a broad bean sauce yeast material; C, carrying out tank type circulation fermentation on the broad bean sauce yeast material by feeding the broad bean sauce yeast material into a fermentation tank with a partition plate arranged at the lower part of a tank body in a radial direction, fermenting by controlling the content of water in the broad bean sauce yeast material in the fermentation tank to be less than or equal to 50%, controlling the content of salt in the broad bean sauce yeast material to be 12-15% and controlling the temperature to be 21-40 DEG C, adding lactic acid bacteria powder accounting for 0.1-0.4% of the total weight of the material during initial fermentation after fermenting for 13-15 days, continuing to ferment for 3-4 days, then adding lactic acid bacteria powder accounting for 0.1-0.4% of the total weight of the material during initial fermentation and continuously fermenting; and totally fermenting for 45-75 days to obtain the broad bean sauce. Through the method, the preparation cycle of the broad bean sauce is shortened; the outside pollution in the preparation process is avoided; meanwhile, the unique flavor of the conventional bean sauce is still retained; the method is small in occupied area and is suitable for large-scale industrial production; the market requirement of the Pixian bean sauce can be met.