This paper reviews frequency resolved optical gating (FROG) femtosecond pulse width measurement technology. Based on analyzing the principles of FROG, the change and development of measurement technology in theory as the main line, the research status and development direction of different structures of FROG measurement are introduced according to three different transient responses of nonlinear effect, which are third-order nonlinear effect, second-order nonlinear effect and cross-phase modulation (XPM) effect. And the characteristics of three types of branch technology are analyzed comprehensively. Comparing different structures of FROG measurement in detail, their strengths and weaknesses and prospects are obtained. It provides research mentality and references for FROG femtosecond pulse width measurement technology.