  The atomic parity non-conservation(PNC) experiments has reached accuracies
which have important implications for physics beyond the standard model. An
optical rotation experiment to measure the atomic PNC of the
3P1(6s6p)--1P1(6s6p) in Yb was proposed recently. Our screened
electron-electron coulomb potential multi-configuration Dirac-Fock calculation
of th PNC induced E1 transition amplitude of this transition E1_PNC = -96.0 x
10^{-11}iea_0(-Q_W/N) of 171Yb is more than two orders of magnitude larger than
E1_PNC(6s-7s) = -0.8991 x 10^{-11}iea_0(-Q_W/N) of 133Cs.
