Abstract: The present invention relates to a compound as represented by formula (I), which is a condensation product of a theanine derivative and a carboxylic acid coumarin derivative, compounds as represented by formula (II) and formula (III), both of which are intermediates of the condensation product, a method for preparing these compounds, a pharmaceutical composition comprising the compounds, and a use thereof in preparing a medicament for prevention and treatment of tumors, inflammation, cardiovascular diseases, immune deficiency diseases and the like.