A study of the cross-linking of beta-galactosidase on magnetic beads is reported here. The magnetic beads were prepared from artemisia seed gum, chitosan, and magnetic fluid in the presence of a cross-linking regent (i.e., glutaraldehyde). The reactive aldehyde groups of the magnetic beads allowed the reaction of the amino groups of the enzymes. The animated magnetic beads were used for the covalent immobilization of beta-galactosidase. The effect of various preparation conditions on the activity of the immobilized beta-galactosidase, such as immobilizing time, amount of enzyme, and the concentration of glutaraldehyde, were investigated. The influence of pH and temperature on the activity and the stability of the enzyme, both free and immobilized, have been studied. And o-nitrophenyl-beta-D: -galactopyranoside (ONPG) was chosen as a substrate. The beta-galactosidase immobilized on the magnetic beads resulted in an increase in enzyme stability. Optimum operational temperature for immobilized enzyme was 10 degrees Celsius higher than that of free enzyme and was significantly broader.