The invention provides string instrument sounding like cattle, which comprises a resonator, a plurality of strings, a beam, a line connecting plate, a line adjustor, a line adjustor fixing plate, an upper accordatura key, a lower accordatura key, a sound post and a bow; three strings are arranged in parallel, which are respectively treble string, alto string and bass string; a semicircular groove is respectively arranged in the middle of both sides of the resonator; an arc gap is arranged at the top right corner of the resonator; a plurality of peacock holes are arranged on front panels of both sides of the strings. The string instrument provided by the invention has the following advantages: the structure is simple, the shape is beautiful, the tone is loud and clear; the string instrument can sound like cattle vividly and can sound powerful bass based on the combination of size of the resonator, the length of the beam, the distance between the lower keys and the bottom of the resonator, and the thickness of the strings; in this way, the absence of Mongolian bass instruments is filled; three or four tones can be sounded without adjusting the strings; the string instrument is applied to several situations; and the string instrument sounding like cattle can be used as the special accompaniment musical instrument of ''Mongolian singing and musical performance'' based on the special tone.