  Schwinger operator method is applied for studying CP-odd pure gluonic
effective Lagrangian in the Standard Model at three-loop level. The induced
$\theta$-term vanishes by the same reasons as EDMs of quark and W-boson to
two-loop approximation. A simple way is found to demonstrate these
cancellations. All other terms of the effective Lagrangian acquire
non-vanishing contributions. The effective operator of dimension six, Weinberg
operator, is calculated explicitly. The corresponding contribution to the EDM
of neutron is much smaller than that comes from large distances.
