Technology life cycle analysis is one of the most commonly used methods in patent quantitative analysis. By analyzing the development stage of patent technology, we can infer the future development direction of technology. Its research object can be the life cycle of the technology represented by a patent document, or the life cycle of the whole technology in a certain technical field. Through the analysis and research on the relationship between the number of patent applications or the number of patents obtained and the relationship between the number of patent application enterprises and the time series, it is found that patent technology theoretically follows four stages: technology introduction period, technology development period, technology maturity period and technology elimination period.