Network bandwidth and hardware technology are developing rapidly, resulting in the vigorous development of the Internet. A concept, cloud computing, uses low-power hosts to achieve high quality service. According to the characteristics of cloud computing, the cloud service providers can support the service applications on the Internet. There are a lot of applications and data centers in the cloud-computing environment, then the loading of storage node is heavier than before. However, data deduplication techniques can greatly reduce the amount of data. Therefore, an integer Bloom Filter based Lightweight Deduplication Mechanism (LDM) under cloud storage is proposed. The proposed LDM can reduce the extra cost that traditional data deduplication technique needed.