The Mm0.3Ml0.7Ni3.55Co0.75Mn0.4Al0.3 metal hydride electrodes were prepared at pressure-holding time of t (t=10, 15, 20 and 25 min). The effects of the pressure-holding time on the activation performance, maximum discharge capacity, discharge potential characteristic and cycle stability of the electrode were investigated. The mechanism of the effect of the pressure-holding time on the electrochemical properties of metal hydride electrodes was also discussed in detail. The results show that the pressure-holding time has no effect on the activation performance of the electrode basically, and the other electrochemical properties of the electrodes are improved firstly and then degenerated with increasing of pressure-holding time. The electrode at pressure-holding time of 15 min exhibits the best electrochemical properties. The improvements of the electrochemical properties are attributed to the increase of the charge-transfer reaction rate on the alloy and the decrease of the internal resistance of the electrodes