Objective A drainage ware was designed for postoperative care after functional endoscopic sinus surgery. It can prevent the ostium of maxillary sinus from closing, drain the empyemata from maxillary sinus and send the medicament to the field of ostiomeatal complex. Methods Based on the results of numerical simulation of airflow in nasal cavity and the data obtained from Rhinomanometry, the characters of airflow in the middle nasal meatus were acquired. According to the characters, right boundary conditions for the following calculation were assigned. The numerical model of drainage ware was generated. Based on the tow-phase flow theory and finite-volume method, numerical simulation for the liquid in the drainage ware was performed to explain how the drainage ware did its work of draining the empyemata from maxillary sinus and sending the medicament to the place around the surface of wound. By changing the value of tube diameter or viscosity parameters of liquid-phase flow, different results of numerical simulation were acquired. Results After comparing the computational results, the fit value of drainage tube diameter was obtained. Conclusions Through numerical simulation for two-phase flow in the drainage ware it proved that the drainage ware designed in this way can accomplish the work of keeping ventilative, draining the empyemata, sending medicament and preventing the ostium of maxillary sinus from closing.