Effects of phosphorus deficiency in the medium on growth and morphology and activities of SOD and POD, utilization of nitrogen and calcium in the medium during liquid culture of Cucumis sativus hairy roots were investigated. The results showed that C. sativus hairy roots can not grow in the medium without addition of any phosphorus. When cultured into the medium with different Pi concentrations, the growth of C. sativus hairy roots was significantly inhibited with the decreasing of Pi concentration in the medium, its main roots became thinner and longer, the number of its lateral roots was decreased and its lateral roots became shorter and smaller. Compared to the medium with full strength phosphorus, the content of soluble proteins in C. sativus hairy roots cultured under Pi deficiency was significantly lower than that with standard full-length Pi, while POD and SOD activities in C. sativus hairy roots were significantly stimulated. Compared to the control (without addition of any phosphorus in the medium), the activities of POD and SOD in C. sativus hairy roots cultured in the medium with different concentration of Pi were lower than the control. When C. sativus hairy roots were cultured into medium with different Pi concentrations, the medium conductivity was gradually decreased with time and with direct proportion of the initial Pi concentration of the medium; NH4+-N and NO3--N of the medium was gradually absorbed and utilized, at day 15, NH4+-N of the medium was nearly used up but its NO3--N was not used up until cultured for 30 days. Pi deficiency in the medium could decrease the consumption rate of NO3--N and inhibited the absorption and utilization of calcium of the medium by C. sativus hairy roots. Proper enhancement of Pi concentration could stimulate absorption and consumption of calcium of the medium.