The large odd-even difference in moments of inertia between the SD bands 195T1(1,2) and 196Pb(1) is investi gated by the particle-number conserving method, in which the blocking effect on pairing is taken into account strictly. The w variation of J(2) for the three SD bands are reproduced quite well and the underlying microscopic mechanism is demonstrated clearly. Calculations show that the blocking of the proton [642]5/2 intruder orbital and the excitation of [651]1/2 intruder orbital play crucial roles for the odd-even difference in J(2) s.