A series of bulk (La1-xPrx)2/3Sr1/3MnO3 polycrystaline samples were prepared by sol-gel technique and the electrical, magnetic properties and magnetostriction effect were studied. At low temperatures, the magnetostriction was mainly about linear magnetostriction and saturated at low magnetic field, and the saturation field decreased with decreasing Pr content. At x=0.3, we found maximum value of -90×10-6.