Abstract: Disclosed is a system integration method based on a system entity structure (SES). The method comprises steps of (a) analyzing an integration target system to extract a technology attribute and to represent the integration target system as a system entity structure (SES); and (b) carrying out a pruning operation for constitution elements of the integration target system represented as the system entity structure (SES) in the step (a), in consideration of the technology attribute extracted in the step (a), an environmental factor and a pruning rule, which being a basis for selection of constitutional technological elements. The invention is particularly effective for an integration target system having various element technologies such as information security system.