In order to study the influence of nozzle area adjustment of afterburner connection of turbofan engine at high-altitude, the flight test was carried out. During the flight test, after the successful ignition at the starting stage of afterburner, the insufficient expansion of nozzle area led to a sharp increase in the pressure behind the fan, and the engine cut-off the afterburner actively. When the fuel flow of afterburner was increased after the successful afterburner ignition, the excessive expansion of nozzle area led the afterburner flameout due to lower pressure. By adjusting the control parameters of the nozzle, increasing the expansion extent of the nozzle area during the ignition, the performance of the afterburner connection was improved, and reducing the expansion extent of the nozzle area at the time when oil supply increase, the afterburner was capable of sustained and steady combustion. The test results show that the adjustment of the nozzle area control law can significantly improve the ability of reheat lit, which can be used for reference for the design and improvement of other turbofan engines.