[Context]　Establishing　requirements　models　is　an　effective　way　to　analyze　them,　which　is　typically　dealt　with　in　a　graphical　manner　(i.e.,　the　drag-and-draw　fashion).　However,　as　the　size　of　models　increases,　the　scalability　issue　has　become　an　unignorable　challenge,　hindering　the　practical　adoption　of　requirements　modeling　approach.　Some　researchers　have　recently　proposed　and　promoted　textual　modeling　approaches,　mitigating　these　issues　of　requirements　modeling.　[Objective]　In　this　paper,　we　aim　at　evaluating　the　two　modeling　methods,　i.e.,　a　graphical　modeling　method　VS.　a　textual　modeling　method.　In　particular,　we　apply　these　two　methods　to　iStar　modeling　language,　which　has　been　widely　recognized　as　an　effective　means　to　model　and　analyze　requirements.　[Methods]　We　have　systematically　designed　and　conducted　a　controlled　experiment　with　38　participants　to　compare　two　iStar　modeling　methods　(graphical　and　textual)　using　two　corresponding　modeling　tools　(piStar　and　T-Star).　The　experimental　results　reveal　that　the　numbers　of　iStar　model　nodes　and　relationships　built　by　the　participants　had　no　significant　difference,　regardless　of　the　modeling　method　adopted.　[Conclusions]　First,　the　results　show　that　the　textual　modeling　method　is　as　usable　as　the　graphical　modeling　method　when　creating　iStar　models.　Second,　we　have　identified　a　number　of　issues　that　contribute　to　improving　the　utility　and　practicality　of　the　iStar　modeling　method.