Objective To observe the imagelogy feature on the change of hippocampal morphous and volume of Alzheimer disease for offering base of clinical diagnosis and differential diagnosis.Methods Utilizing Siemens 3.0T MR to scan hippocampus of 20 AD patients and 20 normal controls in inclined coronal position,then analysis the status of hippocampal volume changing,and compare the hippocampal morphous by analysis areas of scanning slice and number of layers.Results The volume of whole hippocampus and hippoeampal head and body was smaller than normal control's(volumes of right hippocampus:control group(2405.0±278.4)mm~3,AD group (1919.2±201.7)mm~3,t=6.32,P<0.01;volumes of right hippcampal head:control group(1256.2±261.4)mm~3,AD group(913.4±213.2)mm~3,t=4.54,P<0.01;volumes of right hippeampal body:control group (738.3±118.5)mm~3,AD group(613.1±109.8)mm~3,t=3.47,P<0.01;volumes of left hippocampus:control group(2412.5±248.9)mm~3,AD group(1931.0±214.5)mm~3,t=6.55,P<0.01;volumes of left hippcampal head:control group(1238.1±228.9)mm~3,AD group(920.8±205.2)mm~3,t=4.62,P<0.01;volumes of left hippcampal body:control group(741.0±120.7)mm~3,AD group(627.6±111.3)mm~3,t=3.09,P<0.01).By analysising the morphology,the number of layers of AD patient's hippocampal head was obviously smaller than normal control's(right:control group(9.3±2.7)layers,AD group(6.8±2.1)layers,t=3.27,P<0.01;left:control group(9.5±3.0)layers,AD group(6.7±2.9)layers,t=3.00,P<0.01),that was the long axis of AD patient's hippocampal head became short,as the areas of scanning slice had no statistical change(P>0.05 all).Conclusions The decreasing volumes of AD patient's hippocampal head and body is mainly reason of smaller whole hippcampal volume.The long axis of AD patient's hippocampal head became short.Both of the changes that above-mentioned may be the feature of the imageology. Key words: Hippocampus; Nuclear magnetic resonance; Alzheimer disease volume; Morphous