Object-Based storage is a good choice for large scale storage systems. Load balancing of metadata is important to improve the performance of I/O. The existing load balancing schemas cannot evenly distribute the accesses of metadata in a dynamic way. Moreover, the adaptability and fault-tolerance ability need to be improved. This paper presents an adaptable distributed load balancing of metadata (ADMLB) which is composed of basic load balancing algorithm (BBLA) and distributed incremental load balancing algorithm (IBLA). Specially, ADMLB first uses BBLA to distribute metadata loads according to the performances of the metadata servers and then uses IBLA to incrementally reorganize loads on each metadata server. ADMLB can evenly distribute loads between metadata servers and adapts well to the changes of loads. It also has good fault-tolerance ability, and locates metadata servers very quickly.