Abstract: Through analyzing quantum communication in the token-ring network of three-particles entangled GHZ state，two articulation points are found and the fidelity is calculated.The calculation results show that the maximum fidelity is 1 for |a|=0,|b|=1 or |a|=1,|b|=0.For |a|=|b|=2/2,the fidelity is 0.5.The average  fidelity is 0.67 at Bell-state measurement.With Von Neuman measurement,the fidelity relates to analyzer angle θ.If θ=π/4±kπ （k=0,1,2,…），the maximum  fidelity is 1;if θ=π/4±kπ/2/（k=0,1,3,5…），the minmum of the fidelity is zero.The average  fidelity is 0.5 .

Key words: quantum communication, teleportation, GHZ state, fidelity