The invention discloses a gentle type yellow mustard sauce easy to smear and a preparation method thereof, and belongs to the fruit and vegetable food processing technical field. The product is prepared through activation, preliminary crushing, superfine grinding, heating dissolving, stirring, fermentation, compounding, ultrasonic emulsification and sterilization. Yellow mustard seeds are subjected to low-temperature crushing, so that myrosase activity is protected, enzyme inactivation is avoided from being caused by high temperature, allyl isothiocyanate is fully generated from glucosinolate in the mustard seeds, and thus the production of other bitter substances is reduced. With addition of a right amount of soybean protein, the stability of allyl isothiocyanate hydrolyzed from the mustard powder is improved, and main flavor substance isothiocyanates are not easy to volatilize. With addition of sorbitol, the water activity of the yellow mustard sauce is reduced, hydrolysis of allyl isothiocyanate is inhibited, and the flavor of the yellow mustard sauce is extended. Beta-cyclodextrin is added for embedding allyl isothiocyanate, so that the product is mellower in taste, tastes gentle and does not produce stimulation of nose choking, and the acceptable degree of the product is increased. Intermittent ultrasonic emulsification homogenization makes the yellow mustard sauce be more homogenous and have better smearing property, and flexible sterilization is adopted at a later period so as to better retain the flavor of the product.