Abstract: The coupling factor F1 from the mitochondria of the mung bean etiolated seedlings had been isolated and preliminarily purified. The results showed that the coupling factor F1 we obtained had ATPase activity. The activity in the preliminary purifying preparation was about 54 times as high as that of ATPase activity of the original mitochondria, and the activity to hydrolyze ATP had reached 2.14 μmole/min/mg protein. The optimum pH of the coupling factor F1 from mung bean seedlings was about 8.5, and the optimum temperature was 45 ℃. The coupling factor F1 from mung bean mitochondria was cold labile. When the F1 was resolved from the mitoehondria inner-membrane and was in soluble form, it lost the sensitivety to DCCD. The coupling factor F1 of mung bean mitoehondria was Mg++-dependent, and it was activated by DNP, but the activation by Ca++, NaCl and KC1 were not observed. The molecular weight of the coupling factor F1 was about 380,000 as shown by gel electrophorsis.