1. A computer-implemented method for extracting business rules of Service-Oriented Architecture (SOA) system, the method comprising: obtaining one or more values of a plurality of business objects; obtaining one or more structure units of the SOA system; establishing one or more association relationships between the one or more structure units and the one or more values of the plurality of business objects, wherein an association relationship comprises one of a value of a business object that is an input of the structure unit and a value of a business object that is an output of the structure unit and further comprises a corresponding relationship between a value of a business object as an input of the structure unit and a value of a business object as an output of the structure unit with respect of the structure unit; and generating one or more business rules based on the one or more association relationships by: determining a condition of each of the one or more business rules; determining an action of each of the one or more business rules; and linking the condition of each of the one or more business rules and the action of each of the one or more business rules based on at least one of the one or more association relationships to generate the business rule.