Abstract: Using the detailed configuration accounting with the term structures treated by the unresolved transition array model, we present a method to calculate the transmission spectra for highpower laserproduced plasmas in local thermodynamic equilibrium. Based on the quantum defect theory, the UTA parameters with high principal quantum numbers can be conveniently calculated with much less computational efforts. This ensure us to handle a huge number of transition arrays from many configurations occurrin g in typical laserproduced middle Z and high Z plasmas．