Abstract: In order to exactly understand the high performance of the plug nozzle with two-dimensional rectangular inner cells,a two-cell test plug nozzle was designed,and numerical and experimental studies were conducted for such a model.The numerical simulation was based on an Non-Oscillatory and Non-Free Parameters Dissipation Difference （NND） scheme to solve the three-dimensional Navier-Stokes equations,and the cold flow experimental studies using air were performed to evaluate the nozzle performances.The model studied has a nozzle throat area of 4×60 mm²,with the inner nozzle area ratio of 4 and total area ratio of 24.05.The nozzle was designed for the pressure ratio about 500.The flow field and plug pressure profiles were obtained.The results show a good agreement with experimental data,and the maximum discrepancy is by 1%.The model has high nozzle performance with the maximum thrust coefficient efficiency of 0.995,and has good altitude compensation characteristic comparing with the bell nozzle that the nozzle efficiency is in the range of 0.97～0.995 with the pressure ratio changing from 45 to 600.The plug surface pressure profiles for the full-length plug nozzle at different NPR can provide valuable data for researching the truncated plug nozzle.