Some of ion beam properties have been investigated by using Lee model code on plasma focus devices which is operated with nitrogen and helium gases. The operation of plasma focus in different pressure regime gives a consistent ion beam properties which can make the plasma focus a reliable ion beam source .These ion beam properties such as ion beam flux, ion beam fluence, ion beam energy, ion beam current, and beam ion number corresponding to gas pressure have been studied for Mather type plasma focus device. The result shows the differences between helium as lighter gas and nitrogen as heavier gas in term of ion beam properties. The fluence and flux are decrease for nitrogen while increase for helium.