  We propose to study the superconducting pairing of quarks with the formation
of the diquarks as well as the quark-antiquark pairing in QCD by means of the
functional integral technique. The dynamical equations for the superconducting
order parameters are the nonlinear integral equations for the composite quantum
fields describing the quark-quark or quark-antiquark systems. These composite
fields are the bi-local fields if the pairing is generated by the gluon
exchange while for the instanton induced pairing interactions they are the
local ones. The expressions of the free energy densities are derived. The
binding of three quarks is also discussed.
