The Ξ0 asymmetry parameters are measured using entangled quantum Ξ0-Ξ¯0 pairs from a sample of (448.1±2.9)×106 ψ(3686) events collected with the BESIII detector at BEPCII. The relative phase between the transition amplitudes of the Ξ0Ξ¯0 helicity states is measured to be Δφ=-0.050±0.150±0.020 rad, which implies that there is no obvious polarization at the current level of statistics. The decay parameters of the Ξ0 hyperon (αΞ0,αΞ¯0,φΞ0,φΞ¯0) and the angular distribution parameter [αψ(3686)] and Δφ are measured simultaneously for the first time. In addition, the CP asymmetry observables are determined to be ACPΞ0=(αΞ0+αΞ¯0)/(αΞ0-αΞ¯0)=-0.007±0.082±0.025 and ΔφCPΞ0=(φΞ0+φΞ¯0)/2=-0.079±0.082±0.010 rad, which are consistent with CP conservation.