Abstract: Ninety sexually mature fish (Monopterus albus) were selected and divided into the experimental and control group. After LHRH-A was injected, the enzyme sites and changes in the activity of the alkaline phosphatase (ALP) and acid phosphatase (ACP) in the oocytes of M. albus were determined using Gomori histochemical method and king-Altman method, respectively. The result shows that ALP is located in the folliculi and zona radiata while ACP is located only in the folliculi. Whan the oocytes are reaching final maturation (72 hours after injection), ALP activity in the experimental group is significantly higher than that in the control group (p0.01). In the experimental group, the ALP activity of 72 h is also significantly higher than that at 0, 48 and 96 h after injection (p0.05). Prior to spawning (96 hours after injection),ACP activity in the experimental group is higher than that in the control group (p0.01); it is also significantly higher than that in the experimental group at other times (p0.01). Both ALP activity and ACP activity decrease significantly after spawning (p0.05). It is suggested that the increase in ALP and ACP activity bears direct relationship to the maturation and spawning of oocytes after injection.