The opening and closing of stomata control the diffusion of CO₂ and water vapor, and accurate modeling of stomatal conductance (g_s) is essential for predicting global water and CO₂ fluxes. The Ball-Berry and Medlyn models with key slope parameters (m or g₁) have been widely used to estimate g_s. However, there are few studies on quantifying the model parameter values of different tomato genotypes and analyzing their relationship with physiological traits under salt stress. Here, we fit m and g₁ of tomatoes using stomatal response curves and analyzed their correlations with physiological characteristics under five genotypes and two salt treatments. m was significantly different while g₁ was more stable among genotypes, and salt stress significantly reduced them. By testing differences in regression slopes or intercepts, the relationships between leaf water status, and biochemical and stomatal development are found to be uniform among tomato genotypes. Osmotic potential, pre-dawn leaf water potential and abscisic acid (ABA) are driving factors for g_s model parameters. Structural equation modeling showed that ABA directly modulates model parameters, not through leaf morphology or stomatal development. Overall, this study quantified g_s model parameters and identified driving factors for different tomato genotypes under salt stress, providing a practical approach to model water and carbon fluxes under salt stress.