Cloud computing, as a computing method based on Internet, allows varieties of shared hardware and software resources being provided through terminals or devices. Like all other Internet-based services, performing tasks in the cloud could consume resources. Thus using resources effectively is an important subject for the cloud service provider. In this thesis, we classify two cases of cloud environment and propose several algorithms to reduce cloud configuration cost based on them. For each algorithm we analyze the performance of it in detail and justify it by real world data.