  Being one of the golden channels for precise measurement of Higgs properties,
the process $gg \to H\to ZZ \rightarrow 4l$ provides an opportunity to detect
the anomalous $HZZ$ couplings in searching of new physics beyond the Standard
Model. In this paper, we adopt the method of spinor helicity amplitudes to
calculate the amplitudes of process $gg \to H \to ZZ \rightarrow 2e2\mu$ at the
LHC in the frame of the effective dimension-6 operators. Signal processes of
CP-even and CP-odd anomalous $HVV$ couplings in Higgs on/off-shell region and
their interference are simulated by using the package MCFM. The most sensitive
angle $\phi$ to extract the CP violated $HZZ$ coupling coefficients, which is
defined as the angle between two $Z$ decay planes in Higgs rest frame, is found
for experimental measurements.
