The goal of the current study is through the use of quality-by-design software a simple, robust, specific, and accurate stability-indicating liquid chromatography (LC) methodology (reverse-phase high-performance LC) was created for the estimation of Lopinavir. Water's HPLC System with a photodiode array detector at 250 nm was used for the chromatographic separation. The method was created using methanol-potassium dihydrogen orthophosphate (pH 3.8; 10 mm, tetra butyl ammonium hydroxide; 10 mm (40:60, v/v)) on a Lichrospher RP C18 (250×4.6, 5 mm) column with a flow rate of 1.55 ml/min at 55°C. According to the International Conference on Harmonization (ICH) criteria. Results were chosen as independent variables (critical analytical attributes) for the method optimization. (20 runs, 3 levels, and 3 factors) were carried out with Design Expert Software. LOD, LOQ, Specificity, and Robustness were carried out. The lopinavir HPLC method that is provided is accurate and simple. The developed method shows good accuracy, precision, linearity, specificity and system compatibility.