The use of membranes for separation and purification of gases, vapors and process liquids compared to other technologies such as absorption and distillation known, attractive process for oil, gas and petrochemical industries؛Because the membrane technology are low cost, low power consumption (In terms of energy) and compatible with the environment.In this study, a group of polyurethane based on hard segments containing of toluene diisocyanate (TDI) and 1, 4-butane diamine (BDA) and soft segment consisting ofpolypropylene glycol (PPG) with molecular weight 2000 g/molewere synthesized. The polymer was synthesized in mole ratios of 1:3:2 of diisocyanate: chain extender: polyol by bulk two-step polymerization.To investigate the effect of zeolite particles on permeability properties of polyurethane and improve it, mixed matrix dense membranes of polyurethane/zeolite were prepared by using thermal phase inversion method and evaluated pure gas permeability of nitrogen, oxygen, methane and carbone dioxideat constant temperature and pressure. To study the effect of zeolite type on the performance of gas separation membrane,the permeability of polyurethane–zeolite 3A, 4A and ZSM-5 wereinvestigated. The permeability of nitrogen, oxygen, methane and carbon dioxide were determined using constant pressure method. In order to make meaningful tests and obtain process optimization, response surface design and analysis by design expert6 software and central composite design (CCD) was used. Zeolite concentration, temperature and pressure were selected as the main parameters and in the 0-24wt%, 25-45 ?C and 2-10 bar regions, respectively.The results of analysis showed that the effect of increasing zeolite concentration was more influence. Also, the optimal operatingconditions are in the area between of defined ranges. By using design expert6 software, optimal points of parameters are achieved in zeolite concentration 18wt%, temperature 30?C and pressure8bar. As it was expected with increasing the temperature, not only the permeability of all gases was increased, especially for more condensable gases this increase with higher intensity were visible but also all the selectivities were decreased. It was observed that with increasing the pressure, selectivities increased. The prepared polyurethane-zeolite membranes were characterized using FTIR and SEM. The obtained SEM micrographs and FT-IR spectras confirmed that the zeolite particles distributed in polymer matrix homogenously. Gas permeation properties of polyurethane- zeolite mixed matrix membranes with zeolite content of 6, 12,18 and 24 wt.% was studied for pure gases at 10 bar pressure and at 25°C.Increasing the zeolite particles (from 0 to 24 wt.%) in polyurethane increased permeability and selectivity coefficient for all three types of polyurethane-zeolite mixed matrix membranes in compared with pure polyurethane membrane.The results of gas permeation experiments represented that polyurethane-zeolite 4A is the most suitable membrane because of the pore size of zeolite 4A. Because zeolite 4A pore size was appropriate for the separation of selected gases. The Permeability of condensable gases in comparison to non-condensable ones more increase by increasing the zeolite content in polymer Structure. Also, the selectivity of condensable gases in polyurethane considerably increased. The permeability of CO 2 and itsselectivity over N 2 was increased from 69.01barrer and 16.36in pure polyurethane to 95.81barrer and 22.08in thezeolite3A-mixed matrix membrane containing 24wt. % of zeolite particles. The permeability of CO 2 and itsselectivity over N 2 was increased from 69.01 barrer and 16.36 in pure polyurethane to 109.37 barrer and 22.84 in thezeolite4A-mixed matrix membrane containing 24 wt. % of zeolite particles. The permeability of CO 2 and itsselectivity over N 2 was increased from 69.01 barrer and 16.36 in pure polyurethane to 119.34 barrer and 21.21 in thezeolite ZSM-5-mixed matrix membrane containing 24 wt. % of zeolite particles. Keywords: Polyurethane membrane, mixed matrix membrane, polyurethane, zeolite particles, Gas Separation.