The compositional periods of Johann Christian Bach, the youngest son of J. S. Bach, include Berlin, Italy, and London, and the keyboard concertos were written in Berlin and London. The works written in Berlin period were influenced by his brother, C. P. E. Bach, and the styles of those concertos written in London were created under the musical atmosphere of London society. The thesis is a study of the relationship between the London musical society and keyboard concertos of J. C. Bach. The discussion includes three chapters, in addition to the introduction and conclusion. Chapter one is the general discussions about the composer, the development of solo concerto, and historical background of the keyboard concerto in London. The second chapter focuses on the musical society in London in the second half of the eighteenth century. The third chapter contains detailed discussions of the style differences of the keyboard concertos composed by J. C. Bach between the Berlin and London periods. J. C. Bach was the private music tutor of Queen Charlotte, while traveling in London during 1762 to 1782. At the same time, he also participated in teaching, composing, performing, and organizing public concerts very actively. He wrote three sets of keyboard concertos, opus 1, 7, and 13. Each set includes six concertos, and each of which mainly contains two movements. The style of keyboard works of J. C. Bach are characterized by the pre-classical styles of symmetry and balance of the phrases. The concertos were written mostly for amateurs, and in order to satisfy the necessity of the musical market and teaching, the skill of the solo part was not technical demanding, they were simple. The concertos were composed for both harpsichord and piano, but more intended for the piano instrument, especially opus 7 and 13. The wealth economy, the improvement of manufacture techniques of the keyboard instrument, the prevailing public concerts, and the musical needs for Royal family and amateur musicians in London were the important reasons that effected the stylistic changing of J. C. Bach¡¦s writing of keyboard concertos.