A partition-based method for diagnosing memory leaks in Java systems, comprising dividing heap memory of a Java virtual machine into a plurality of partitions based on a partition plan, wherein each partition has at least one partition owner; monitoring the status of the respective partitions to determine whether there is a partition in which the memory space is exhausted; and if there is a partition in which the memory space is exhausted, determining that the memory leak may occur in the partition and analyzing the partition to obtain leaked objects and objects related to the leaked objects. The present invention also provides a partition-based apparatus for diagnosing memory leak in Java systems.