Fumigation has been the most convenient method in the field of pest control in museums. In this study, as fumigants, ethanol 70%, deltamethrin (commercial pesticide (CP) ) , essential oil (EO) from Pinus regida, and low oxygen microenvironment (0.1%, (LOM) ) were tested individually and jointly against museum fungal strain Alternaria alternata. Three concentrations of each CP and EO were chosen for evaluating the individual effect. In the joint action fumigation process, three lower concentrations of CP and EO were tested in LOM. The rate of mycelial growth inhibition at each fumigation process was determined by two steps: 1) directly after the fumigation process and 2) after 7 d of the inoculation of the fumigated spores in new medium and incubating it in normal condition. The results demonstrated that applying of each chemical (CP or EO) in LOM enhanced its fungicidal activity and that effect of EO improved from fungistatic to fungicidal by jointing with LOM.