A pentaerythritol chiral spirocyclic compound is characterized by being a chiral spirocyclic compound which can be compounded by substituted benzaldehyde and pentaerythritol, also can be split and contains the construction unit of pentaerythritol. The synthetic method comprises the procedures of charging materials, adding with a catalytic agent, stirring, filtering, recrystallizing, etc. The splitting method is as following: dissolving the compound in a moving phrase, and then carrying out chiral separation to the compound in a high-effective liquid chromatograph by a chiral column. The invention has the advantages that the chiral spirocyclic compound can be used as the intermediate compound of a novel chiral axial medicine and also can be used as a medicine monomer to be induced in different active functional groups; pure optical isomer is obtained by splitting an external racemic body, thereby increasing the safety of medince and having significance in pharmacodynamics and medicine dosage. In the synthetic process, environement friendly synthetic method is applied, thereby having low cost and convenient operation, and being beneficial to protecting environment and belonging to green chemistry.