Dominant spin-flip effects for the direct and prompt J/ψ polarizations at TEVATRON run II with collision energy 1.96 TeV and rapidity cut |y J/ψ | < 0.6, have been systematically studied, especially, the spin-flip effect for the transition of (cc) 8 [ 3 S 1 ] into J/ψ has been carefully discussed.It is found that the spin-flip effect shall always dilute the J/ψ polarization, and with a suitable choice of the parameters a 0,1 and c 0,1,2 , the J/ψ polarization puzzle can be solved to a certain degree. At large transverse momentum p t , α for the prompt J/ψ is reduced by ∼ 50% for f 0 = v 2 and by ∼ 80% for f 0 = 1. We also study the indirect J/ψ polarization from the b-decays, which however is slightly affected by the same spin-flip effect and then shall provide a better platform to determine the color-octet matrix elements.