Water-in-oil (W/O) and water-in-oil-in-water (W/O/W) emulsions with bittern solution as internal aqueous phase were prepared. These emulsion coagulants showed good controlled-release property when used in traditional firm tofu preparation. Compared with the traditional bittern coagulant, emulsion coagulants significantly improved the water content from 70% to the maximum 84% or 79%, as well as increased the yield of tofu gel. In addition, the use of emulsion coagulants modified the tofu gel to be more smooth and homogenous, as well as significantly reduced the hardness of tofu gel while remained the spring and improved the bright. Results also indicated that the loss of protein and soy isoflavones during tofu preparation was decreased, along with a higher yield of soy isoflavones.