Abstract: On the basis of our previous work it has been found that the 1/ƒ noise is a kind of "phase" with a developmental process.And the fact that the 1/ƒ noise can be finally formed or not depends on if the minimum demand for reliability of M^#>500 being satisfied.Moreover this is also a criterion for distinguishing 1/ƒ noise.Subsequently,it can be learnt that the entropy of 1/ƒ noise is S^#=A×10^-20 erg/K and S^# is a minimum for all kinds of 1/ƒ noise,which is their general character.But for different 1/ƒ noise A is a variable value,which represents the individual character of 1/ƒ noise.