Three problems about the concept of validity were discussed here,which is the evolution of concept of validity and its existing problems,a new understanding of validity and how to construct validity.During the development of the concept of validity,content validity,predictive validity,construct validity as well as concurrent validity were prevailing until the emergence of construct validity in which all aspects of validity were involved.To date,the bias we put on the concept of validity were mainly originated from the way by which we have taken concept of validity as a nomological network.Actually,the concept of validity is a ontological claim which is seriously based on reference and causality.We should establish a theory hypothesis,form a test,and confirm the measure attribute,so we could obtain the validity.