The invention provides a memory management method and device of a shared memory database. The method comprises the following steps of: in a space for creating the database, according to the preset maximum value of database capacity, distributing a virtual memory space to the database; distributing a first physical memory to the database, setting the beginning address of the first physical memory as the beginning address of the virtual memory space so as to bring convenience for inserting or revising data in the first physical memory; judging whether the idle memory of the database is smaller than a preset threshold value or not so as to obtain a first judgment result; when the first judgment result shows that the idle memory of the database is smaller than the preset threshold value, adding a second physical memory with a preset dilatation step size into the virtual memory space of the database, and setting the beginning address of the second physical memory as the tail address of the previous physical memory; and expanding the available memory space of the database. By use of the method, the problem that the address of a multistage shared memory database is discontinuous can be solved, and management complexity caused in a way that the shared memory needs to be remapped when the multistage shared memory database is subjected to dilatation is simplified.