To achieve accurate prediction of aluminum alloy formability limits, a material hardening model based on the interpolation method of measured stress-strain data was proposed. The theoretical formability limit predictions of measured data, the power exponential, and cubic polynomial hardening models were systematically studied using the M-K theory. Uniaxial tensile tests were conducted to obtain stress-strain data of 6016 aluminum alloy, based on which different material hardening models were constructed. Detailed calculation procedures for limit strains under various models were presented, and forming limit diagrams (FLDs) were plotted. Finally, experimental results of aluminum alloy sheet formability limits were obtained through punch bulging tests and optical non-contact measurement techniques. The results indicate that the material hardening model based on the interpolation method of measured data demonstrates superior prediction accuracy, showing perfect agreement with experimental results. In contrast, commonly used power law and cubic polynomial curve-fitting hardening models tend to overestimate formability limits, particularly under negative strain path conditions. Material hardening models significantly influence the prediction of forming limits for 6016 aluminum alloy sheets, with prediction accuracy positively correlated with the goodness-of-fit of the hardening model fitting curves.