A key blank selector has a base, a template and a clamp. The base defines a chamber and a platform having a recess communicating with the chamber. The template is soft and pliable corresponds to and is detachably mounted in the recess of the platform. The clamp is detachably mounted around the platform of the base to hold and position the template in the recess and has an opening formed corresponding to the chamber of the base. A mother key is positioned perpendicularly on and force applied to pierce through the template and form a figure corresponding to a cross sectional profile of the mother key in the template; therefore, facilitating key blank selection and preventing misjudgment.