The present invention discloses a soy sauce preparation method using maohualu (salt brine separated out in the pickling process of fermented bean curd semifinished product) to replace saline water. The soy sauce preparation method contains the following steps: mixing autolysis treated maohualu with soy sauce koji, fermenting for 180 days, pressing and squeezing, and filtering to obtain the soy sauce. The soy sauce preparation method makes full use of the salt content and nutritional value of maohualu, and the produced soy sauce has more obvious flavor and flesh taste than the fermented soy sauce produced by traditional method.