A fault analysis method based on a data center, wherein component devices of the data center comprise at least two hosts and at least one switching device, at least one virtual machine runs on each host in the at least two hosts, the at least one switching device is configured to establish a communications path between the component devices of the data center, wherein the at least two virtual machines have a communications dependence relationship and run on the at least two hosts form a virtual machine group, and the fault analysis method comprises: obtaining a topology structure diagram, wherein nodes in the topology structure diagram comprise the component devices and the virtual machines that run on the at least two hosts; and obtaining a fault alarm when a fault occurs in the data center; and determining, according to the topology structure diagram, whether the fault reduces communications paths between the virtual machines in the virtual machine group by determining whether a broken communications path exists between the virtual machines in the virtual machine group: characterized in that the method further comprises: wherein the determining, according to the topology structure diagram, whether the fault reduces communications paths between the virtual machines in the virtual machine group specifically comprises: determining a fault ratio of the virtual machine group according to a connection relationship between nodes in the topology structure diagram, wherein the fault ratio specifically comprises a ratio of a quantity of broken communications paths, caused by the fault, between the virtual machines in the virtual machine group to a total quantity of communications paths between the virtual machines in the virtual machine group; wherein the data center has at least two virtual machine groups, and the method further comprises: obtaining an impact level of the fault according to the fault ratio, caused by the fault, of each virtual machine group and a service weight corresponding to each virtual machine group. obtaining a topology structure diagram, wherein nodes in the topology structure diagram comprise the component devices and the virtual machines that run on the at least two hosts; and obtaining a fault alarm when a fault occurs in the data center; and determining, according to the topology structure diagram, whether the fault reduces communications paths between the virtual machines in the virtual machine group by determining whether a broken communications path exists between the virtual machines in the virtual machine group: characterized in that the method further comprises: wherein the determining, according to the topology structure diagram, whether the fault reduces communications paths between the virtual machines in the virtual machine group specifically comprises: determining a fault ratio of the virtual machine group according to a connection relationship between nodes in the topology structure diagram, wherein the fault ratio specifically comprises a ratio of a quantity of broken communications paths, caused by the fault, between the virtual machines in the virtual machine group to a total quantity of communications paths between the virtual machines in the virtual machine group; wherein the data center has at least two virtual machine groups, and the method further comprises: obtaining an impact level of the fault according to the fault ratio, caused by the fault, of each virtual machine group and a service weight corresponding to each virtual machine group. determining a fault ratio of the virtual machine group according to a connection relationship between nodes in the topology structure diagram, wherein the fault ratio specifically comprises a ratio of a quantity of broken communications paths, caused by the fault, between the virtual machines in the virtual machine group to a total quantity of communications paths between the virtual machines in the virtual machine group; wherein the data center has at least two virtual machine groups, and the method further comprises: obtaining an impact level of the fault according to the fault ratio, caused by the fault, of each virtual machine group and a service weight corresponding to each virtual machine group.