Technology Foresight plays increasingly important role in strategy-, policy- and planning-making of science and technology, and therefore receives highly attention from government, academia and the public. The Delphi survey is one of the most popular tools in the technology foresight, in which questionnaire-designing plays critical role. Based on the foreign and domestic experiences in questionnaire-designing for Delphi survey, this paper develops a methodology for Delphi survey including questionnaire-designing, topics selection and statistical method of survey results so as to meet the requirements of .Technology Foresight of China towards 2020. Finally, the paper points out that there are still many questions in methodology concerning future Delphi survey.