Optimized convective heat transfer is applied to accelerate the thermal recovery of a large aperture multi-segment amplifier. The paper proposes a novel project of changing the structural parameters of the inlet jet to the Nd:glass slab in the multi-segment amplifier at the same flow rate. The convective heat transfer coefficient depends on the diameter of the inlet jet, as well as on the number of inlet jets. The simulation calculations indicate that at the same flow rate, different numbers of inlet jet lead to different temperature gradient contours and flow field distributions on the Nd:glass slab surface in the multi-segment amplifier. In addition, the convective heat transfer coefficient increases with the decrease of inlet diameter. This work analyzes the path of the coolant air over the slab surface to lessen the eddy and to achieve better convective heat transfer, as well as to determine the optimized number of inlet jets (5) and the optimized diameter (5 mm)