Abstract: Organization structure is the basic framework of the enterprises and the carrier of all the activities. Its effectiveness means great significance for organization development. In a complex and highly competitive era of knowledge economy, the form of organization structure have been changed a lot and increasingly complexity and uncertainty of external environment make the complexity become an important feature of the organization structure. Currently, There is little study on the organization structure complexity and the study under the guidance of the complexity is even less. Based on this, the article will combine organization structure complexity and the complexity theory to propose the measurement method of organization structure complexity and basing on the result to make the definition of a complex structure organization, which will become beneficial exploration for follow-up study.