fa عمومى General پژوهشي Research The required storage space and the material handing cost in a warehouse hinge on the storage implementation decision. Effects of storage area reduction on order picking and storage space cost are incorporated. Moreover, merchandises which are in the same shape and can be stored beside each other easily or goods that don't cause any danger like causing a fire if be in touch with each other, can be stored in one class together. In this paper first a multi-objective class based storage model is presented in which two objectives are considered one is the sum of storage space cost and handing cost and the other is the quantitative objective "efficiency of storing products in one class". The demand rates and the second objective are evaluated with linguistic values. Fuzzy dynamic approach will be used to solve the proposed model considering an illustrative example to clarify it. 19 35 http://ijorlu.lahijan.iau.ir/browse.php?a_code=A-10-2-7&slc_lang=fa&sid=1 B. Maleki Vishkaei B.maleki.v@gmail.com 100319475328460060 100319475328460060 Yes Department of Industrial Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran. M. EbrahimNezhad Moghadam Rashti 100319475328460061 100319475328460061 No Department of Electrical Engineering, Lahijan Branch, Islamic Azad University, Lahijan, Iran.