In the development history of liuqin for more than 200 years, various forms of liuqin have appeared, such as the original two-string liuqin, three-string liuqin, four-string liuqin, five-string alto liuqin, seven-string liuqin, and double-resonance box liuqin. The music art of Liuqin has been expanded, and the development space of Liuqin has been expanded.

In the early 1970s, Mr. Wang Huiran further innovated and reformed the liuqin on the basis of the three-string 24-fret liuqin. He cooperated with Xuzhou National Musical Instrument Factory again, and in 1970, he successfully trial-produced the four-string twenty-nine fret. Liuqin. On the basis of the three-string twenty-four fret liuqin, a low-pitched string and five high-pitched frets are added to form a four-string twenty-nine fret liuqin.

The timbre of the four-stringed liuqin is bright and beautiful, the treble is high-pitched and crisp, the midrange is soft and luscious, and the bass is thick and rough, which significantly enriches the expressive ability of the liuqin. In 1970, Mr. Wang Huiran's first four-string liuqin solo "Happiness Canal" came out. The four-stringed liuqin is a series of reforms made on the basis of retaining the original style and advantages of the folk liuqin and according to the needs of the national orchestra to play various pieces of music. The reformed ukulele has many advantages and is very popular.