The invention provides an apparatus for preparing a brain tissue sample, which comprises a cutting rack (1) and a support bench (2). The cutting rack (1) and the support bench (2) are two separable structural bodies, wherein the brain tissue sample (3) is placed on the support bench (2), The apparatus can effectively reduce the adhesion effect during the processes, reduces cutting force, reduces the mechanical properties influence on the brain tissue during a cutting process, and can rapidly obtain the brain tissue sample with the consistent geometric size and shape. The apparatus can mutually separate the cutting rack and the support bench, can directly replace the cutting rack having the different cutting sample sizes and can cooperate with the support bench having different grooves, and the brain tissue samples with different sizes can be cut. The apparatus has the advantages of simple process, convenient operation, high efficiency for producing the samples, easy carrying and low cost.