Coaxial-rigid-rotor helicopter has a huge hub drag in forward flight. In order to analyze the drag characteristics of the hub, a test research using force balance is completed in a 1.4 m×1.4 m wind tunnel. Test variations include wind speed, hub rotating speed, hub model gap and different fairing groups. Test results show that the drag of coaxial hub test model affected by the symmetric smooth hub rotation can be ignored; the gaps between the fairing components have a great influence on the drag of models, and the big gap causes the drag increasing; the separated flow after every fairing component produces strong aerodynamic interaction between each other, and makes the drag increase obviously.