Béla Bartók (1881-1945) is not only a well-known Hungarian musician, but also a folk music collector. In the last year of Bartók''s life, he wrote the viola concerto for the Scottish violist, William Primrose. Nevertheless, Bartók passed away before the work been finished. Few years after, Tibor Serly set all those draft and published it. About fifty years after, Peter( Bartók''s son) read the draft and the published score, found out the difference. For let the real idea of his father been understand, he decied to publish a new version, which is almost alike to the draft. The thesis is basic on the revised version, and compare with the Serly''s version and analysis them.