The aim of this study was to define optimal conditions by using Simplex lattice mixture design for the formulation of sucrose-free chocolate produced in a ball mill. Milk chocolate mass were made using three different polyols including maltitol, xylitol and isomalt along with Stevia as high potency sweetener. The influences of polyols mixtures as sucrose substitutes on rheological properties and main physical quality parameters were investigated. According to the results, the fitted models demonstrated a high coefficient of determination (>= 93%). The optimization of the variables illustrated that utilizing 11.16% w/w maltitol, 8.9% w/w xylitol and 12.93% w/w isomalt produced the optimum milk chocolate with the highest desirability (1.00) without unwanted variations in the rheological and quality characteristics. Also the optimum formulation was produced to validate the optimum model. The sensory analysis of the optimized formulation satisfied the consumer demand.