Since the 1990s, the influencing factors of enterprise entry and exit decisions have been explained from the perspective of fixed cost or sunk cost. And the concept of trade relationship duration of products or enterprises did not appear until 2006. Given its great significance for the steady growth of export trade, most of the literatures begin to analyze the duration of trade relations of countries in survival. This paper sorts out and evaluates the research content, method and conclusion, and obtains many valuable conclusions and enlightenment on this basis, and finally prospects the future research direction.

I. Introduction
II. Research Content on the Duration of Trade Relations
    1. Import Trade Relations
    2. Export Trade Relations
    3. Trade in Services
III. Research Method on the Duration of Trade Relations
    1. Cox Proportional Hazard Model
    2. Stratified Cox Model
    3. Extended Cox Model
    4. Discrete-time Cox Model
IV. Research Conclusions on the Duration of Trade Relations
    1. National Characteristics
    2. Characteristic Variables of Market Structure
    3. Product Characteristic Variables
    4. Enterprise Characteristics
V. Research Outlook
References
ABSTRACT

• Tang Pingjuan(Doctoral Student, Department of Business Administration, in Woosuk University, South Korea.)