Durability and walking comfort are two major factors in the evaluation of carpets’ performance and quality. To achieve the costumers demand, confidence and enthusiasm, the key proprieties associated to these two factors must be guaranteed. The first step to achieve the expected performance quality of carpets is accurate designing of their production or structural characteristics. The main aim of this thesis was planned, firstly, to achieve an accurate and scientific procedures for planning the production characteristics particularly, proper selection of materials and secondly, to introduce a model to estimate the useful life of woolen hand-knotted carpets by the functional properties. For this purpose, 36 woolen hand-knotted carpet samples were prepared including two traditional knot types (symmetrical and asymmetrical knot); two types of wool fineness for pile yar three types of knot density and three levels of pile height. Functional properties effective to estimate of carpets’ useful life were selected. Modeling process based on the factorial design for each of these properties was performed. For each of the functional property, mathematical and stable model was designed using the response surface method (RSM) for analyzing the optimal conditions of materials and production factors. Adequacy of the models was evaluated using the appropriate criteria of model particularly, analysis of residuals and, if necessary, data transformation. Moreover, using extra sum of squares relative importance, or contribution of independent variable in models, was calculated and analyzed separately. Predictive capabilities of models for new observations were also reliably verified. The results showed that wear factor has significant effect on decline of quality of the majority of carpets’ functional properties. Two structural factors of samples i.e. pile density and pile height, and their interaction, showed significant effect to determine the functional properties. Mostly, the optimal range of these two factors, were determined in the range of 45-60 knot/dm and 7-11 mm for knot density and pile height respectively. The fineness of wool fibers showed significant effect on the properties related to surface pile yarns. Generally, carpet samples with symmetrical knots showed rather desirable results in comparison to samples with asymmetrical knots in majority of carpets’ functional properties particularly properties of appearance retention. In the case of properties related to compression performance of surface pile yarns at primary wears, samples with asymmetrical knots showed better results. Using multiple multivariate regression methods, predicted equations system of functional properties with the common independent variables was simultaneously prepared. Reverse equations of this system were prepared. The most outstanding result was to achieve the reverse equation of wear factor. It can be an acceptable model to estimate the useful life of each hand-knotted carpet sample corresponding to the values of functional properties. Validity of these models was acceptably verified. Keywords: Woolen hand-knotted carpet, Functional properties, Response surface method, Multiple multivariate regression.