Abstract: Objective To discuss the reason of adult medicine should consider the factor of weight in view of the excessively extensive adult dosage at present. Methods Illustrating the clinical dosage quantification and individualized principle on the basis of pharmacokinetic; investigating and analyzing dosage of child and adult respectively considering the factor of weight; demonstrating the necessity that adult dosage should consider the factor of weight on the reference to gold zone method that children dosage consider their weight （kg）. Results and conclusion The blood drug concentration which is closely related to curative effect is determined by medicine dosage and apparent volume of distribution. The apparent volume of distribution has a high linear relation with weight. Our survey shows that in most cases we do not consider the factor of weight on adult dosage. The study on children dosage according to their weight shows that dosage has a great impact on curative effect, adverse reaction and drug resistance. Therefore, it is put forward that adult dosage should also consider the factor of weight and do related research. Suggestion on the addition of principles and relevant laws and regulations of adult dosage according to the weights in the national formulary and drug administration law.