The invention relates to a cloud computing technology based fault calculation system and method under an SOA framework, and aims at solving the problems that a fault calculation APP in the prior art has certain constraints, is high in cost and is difficult in updating and maintenance during development and use. The system comprise a client and a cloud server end, the cloud server end comprises a data service unit, a graph service unit, a topology analysis service unit and a fault calculating service unit; and data collection and fault calculation are carried out in the cloud server end, and a structure is sent to the client. The system and method have the advantages that specific characteristics including low coupling, easy maintenance and easy development of the SOA are used, functions including high performance, low cost and strong backup for disaster recovery of the cloud computing technology are fused, a fault calculating application is published in the cloud computing server end in the form of a webpage, it is not required to download, install and configure the client, and the client can access the fault calculating system in a cross-platform and cross-system manner; and the development and maintenance cost is reduced, and the operational reliability and safety are improved.