 The concept of technological trajectory, technological transition, and operation mechanism of technological trajectory are briefly illustrated by use of technology S-curve, then the limitations of the method of S-curve are explained, patent cited indicators “technology cycle time” are introduced. The assumption is proposed， namely, the change of the “technology cycle time” slope can indicate the upgrading of technology and technological progress. By use of the regression model, the assumption is verified. The relation between technological cyclic time and patent quantity is discussed in the end.