  By using the path integral method , we calculate the Green functions of field
strength of Yang-Mills theories on arbitrary nonorientable surfaces in
Schwinger-Fock gauge. We show that the non-gauge invariant correlators consist
of a free part and an almost $x$-independent part. We also show that the gauge
invariant $n$-point functions are those corresponding to the free part , as in
the case of orientable surfaces.
