In this paper, from paperless examination about structural mechanics curriculum, online answer and computer evaluation difficulties about subjective examination questions are analyzed. Program method about guided subjective examination questions and automatic evaluation is proposed. In the VB software platform, with diagram multiplication method computing structure displacement problem, subjective questions online interactive answer and score evaluation mechanism about structural mechanics are described and practical examples are given. Online answer and automatic evaluation result about examination paper include statically determinate bending moment diagram, diagram multiplication method,statically indeterminate structure force method and displacement method, structure inherent characteristics are listed. The method will be provided for paperless examination of mechanical engineering courses.