The invention relates to marinated beef and a processing method thereof. The processing method of the marinated beef comprises the following steps of selecting materials, carrying out cutting, carrying out dicing, carrying out rolling, carrying out marinating, carrying out curing, carrying out material mixing, carrying out internal packing, carrying out sterilization, carrying out post-treatment,and carrying out external packing. According to the flavored beef processed by adopting the processing method, the beef is marinated by using uniformly rolled marinating auxiliary-materials, and thus,better smell-removing effects are achieved compared with marinating by using only salt; moreover, the effect of improving aroma is also achieved when the peculiar smell is being removed. During the process of carrying out curing, curing is performed under low pressure conditions, and seasoning auxiliary-materials are then added so as to carry out material mixing, and thus, the beef has a relatively good flavor under the premise of preserving inherent fresh and aromatic taste of the beef. The prepared marinated beef is soft in first taste, smooth, tender and refreshing in taste, delicious in flavor, and long-lasting in aftertaste; and thus, the marinated beef is capable of promoting appetite of people, as well as satisfying demands of different consumers.