Objective  To investigate the effects of up-regulation of zinc finger and BTB domain containing 20（A20）expression on learning and memory and apoptosis of hippocampal neurons in APPswe/PSE9 transgenic Alzheimer disease（AD）mice.    Methods  Forty APPswe/PSE9 transgenic mice were divided into four groups: control group, AD group, small interfering RNA(siRNA）-AD group and A20-AD group. Adenoviruses carrying high expression of A20 were selected as interfering drugs and Morris water maze was used to observe spatial learning and memory. Western blotting was used to detect the expression of A20. Immunohistochemistry was used to observe the expression of P53 in the CA1 region.    Results  Compared with the AD group, the learning and memory function was mproved, the apoptosis rate of hippocampal CA1 neurons decreased significantly and the expression of P53 in the CA1 region decreased  significantly in A20-AD group mice.    Conclusion  Upregulation of A20 expression can improve the learning and memory ability of transgenic mice, reduce the expression of P53 in hippocampal CA1 region of the transgenic mice.