The optimum pH and temperature for endo-polygalacturonase activity from Jujube were 5.0 and 50℃. The range of its stability to pH was 4.0 to 5.0. The enzyme was inactivated about 35% by treatment at 70℃ for 1 hr. It was found that Ag^+, Zn^(++) and Mg^(++) increased the enzyme activity. In contrast, Ba^(++), Hg^(++), Pb^(++), Ca^(++), Mn^(++), Cu^(++), Fe^(++), Na^+ and K^+ decreased it. The enzyme was inactivated by treatment with malefic anhydride, iodine and 2,4-dinitrophenol. The results indicate that active site is a imidazole group on the enzyme.