The invention discloses an unmanned vehicle driving environment complexity quantification method based on rear invasion and collision time, and belongs to the technical field of automatic vehicle driving. The implementation process of the unmanned vehicle driving environment complexity quantification method and the unmanned vehicle driving environment complexity quantification method are carried out through the implementation steps of the unmanned vehicle driving environment complexity quantification method are provided. The driving environment is divided into eight areas including a front area, a right rear area, a right left area, a right side, a left front area, a right front area, a left rear area and a right rear area. An algorithm is used for detecting and evaluating the driving environment of each area, the problem that a clear quantitative evaluation method does not exist in the complexity of the automobile driving environment is solved, and meanwhile the problem that an existing complexity quantification method has defects in the dimension of a road user with the complexity of the automobile driving environment is solved.