Abstract: Franchise is the effective way for government providing public products and services,and it is also an important means of prevention in the field of private capital into the utilities.However,not all the franchise behavior can achieve the result of prevention,only valid franchise behavior can achieve the unity of legal effect and social effect.Although the legal and the illegal of franchise behavior is closely related to the validity and invalidity,it is not equal.The validity franchise behavior may be not legal,also the legal franchise behavior may be not validity.There are four legitimacy forms that are legal and valid behavior,illegal and invalid behavior,illegal but valid behavior and legal but invalid behavior.Each form has its specific situations,applicable restrictions and legal effects.