Abstract: The effect of four kinds of salt (KCl, KNO3, K2SO4 and PEG) under three different osmotic potential on growth of cucumber seedlings was studied in condition of solute culture. The results showed that: compared with three kinds of inorganic salt at the same osmotic potential, PEG had the highest restrain degree on growth of cucumber. Although amount of soluble sugar and Pro accumulated in cucumber leaves that were treated with PEG was the most, osmotic adjustment ability was the worst. The affective degree of different anion on activity of protect enzyme in cucumber leaves was different . The main reason of injury three different kinds of anions to cucumber was osmotic stress, and ion stress was minor factor within this experiment scope of salt density and treatment time .