Abstract: This paper describes the automation of 3D design and aerothermodynamic analysis of a high pressure, single-stage axial flow turbine driving the compressor of the small gas turbine engine Jet Cat p200 using an analytical method. The specifications of design are based on the reverse engineering of the small gas turbine. Baseline design parameters such as flow coefficient, stage loading coefficient are close to 0.5 and 1.16 respectively with maximum flow expansion in the NGV rows. In the thermal cycle and 1D analysis calculations, the total conditions of all engine stations and all design controlling parameters are determined. In 2D design analysis, the mean line approach is used to generate the turbine flow path and 2D airfoil design, and by using the free vortex law of blading, five blade sections are generated. These sections are at hub, mean and tip and two intermediate sections between hub-mean and mean-tip using an approximate method to the Ainley, Mathieson, Dunham and Came loss model to meet the design constraints. An average exit swirl angle of less than 5 degrees is achieved leading to minimum losses in the stage. Also, NGV and rotor blade numbers are chosen based on the original turbine object. Blade profile is redesigned using the results from blade-to-blade analysis and through-flow analysis using special analytical method, [1]. Aerothermodynamic parameters like pressure ratios, aerothermodynamic power, and efficiencies are computed analytically. The results are compared with the published data in the engine manual.