Abstract: Based on a review of the existing language ability scales and those of language proficiency for specific purposes, this paper puts forward some suggestions on the development of scales for language for specific purposes from five aspects:determination of the purpose, competence framework, descriptor system, establishment of the descriptor pool, and principles of descriptor classification and scaling. It is pointed out that, in addition to the common properties of language ability scales, scales of languages for specific purposes have their own particularity which needs special attention.