Compared with conventional tail rotors， scissor tail rotors exhibit certain noise reduction advantages due to their modulation effect， but suffer from aerodynamic efficiency loss caused by aerodynamic interference between upper and lower rotors. To improve the aerodynamic efficiency of scissor tail rotors， this paper employs overset grid technology to establish a high-precision numerical simulation method based on Unsteady Reynolds-Averaged Navier-Stokes （URANS） equations. The aerodynamic interference characteristics between the upper and lower scissor tail rotors in hover state is investigated. The research systematically analyzes the influence of configuration parameters including scissor angle， airfoil type， and swept blade tips on aerodynamic performance. Unconventional configurations featuring differential collective pitch settings and varying rotor disk radii between upper and lower rotors are proposed and evaluated.Results indicate that： Under constant total collective pitch， the “U”-type scissor tail rotors total thrust shows positive correlation with scissor angle， while upper and lower rotor thrusts demonstrate a seesaw relationship. Moreover， among three typical helicopter tail rotor airfoils， the OA airfoil achieves optimal hover efficiency. Additionally， swept blade tip configuration delays tip stall without improving maximum hover efficiency. For unconventional configurations： increasing lower rotor radius by 10% enhances maximum hover efficiency by 12.5% compared to conventional designs. Appropriately adjusting lower rotor collective pitch （+2° relative to upper rotor） optimizes load distribution， achieving 2.4% overall efficiency gain.