Samples were collected in four seasons at the artificial reef area of Laizhou Bay in 2010~2011. Chemical oxygen demand (COD), dissolved inorganic nitrogen (DIN), dissolved active phosphate (DIP), total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) were measured. Index including the ratio of N/P, organic pollution index A and nutrition index E were used to evaluate the quality of water in different years. The results showed that the content of DIN was significantly reduced in the second year, the content of DIP increased slightly, thus the N/P value decreased from 89.60 to 44.54 due to the changes of DIN and DIP, the result of T-test showed that there was a significant difference of DIN/DIP value in artificial reef area between 2011 and 2010 (P<0.05);However, there was no significant difference in control area(P>0.05). From these results, we can conclude that the artificial reefs can improve the quality of seawater. The result of nutrition index E indicated that the nutrition level of the sea water was relatively low, and there was no significant difference in artificial reef area and control area in 2010 and 2011; The investigation results showed that the organic pollution index A was less than 0 or 1, and there was no significant difference in artificial reef area and control area in 2010 and 2011. All these results indicated that the surveyed area were not polluted by organic material, and the quality of water was in good condition.