As the core of virtually all vocal and instrumental composition in the Baroque music, the basso continuo group had an extremely important role in the sacred cantatas by Johann Sebastian Bach (1685-1750). During the Baroque period, the choice of instruments was sometimes indicated by the composer, but frequently the performers had to determine which instruments were most appropriate for the particular environment and context of the music.When performing the sacred cantatas of J.S. Bach, the conductor must identify and make decisions regarding the choices and combinations of instruments for both figured and sustained continuo part. In some cases the conductor may even consider changing continuo instrument(s), movement by movement, in a cantata in which a significant shift occurs in the texture, orchestration, or dramatic function of singer's line. Since Bach's cantatas are an encyclopedia of Baroque musical style, and models of compositional techniques of the time, understanding the cantatas is a practical and effective way to gain understanding regarding his other compositions. These cantatas also present musical challenges and rewards to choirs and orchestras.In an attempt to achieve a greater understanding and establish guidelines, I will examine and propose six principles and parameters regarding choices and combinations of basso continuo instruments and obbligato instruments, examining a variety of movement types from six different sacred cantatas of J.S. Bach ; Christ lag in Todesbanden, BWV 4; Ich hatte viel bekümmernis, BWV 21; Halt im Gedächtnis Jesum Christ, BWV 67; Herr, gehe nicht ins Gericct mit deinem Knecht, BWV 105; Wachet auf, ruft uns die Stimme, BWV 140, and Erschallet, ihr Lieder, BWV 172.This study will include:1) A critical review of performance practice and historical evidence regarding the basso continuo part in Bach's sacred cantatas2) Using "4 TAV System: Six Parameters" performance considerations and suggestions for instrument choices in basso continuo group for chorus, solo, recitative, and chorale movements in the selected cantatas3) Examinations and suggestions of several possible choices and combinations of basso continuo instruments