Objective To compare the treatment outcomes,complications and histopathologic features between conventional parotidectomy and functional regional parotidectomy in the treatment for pleomorphic adenoma of parotid gland and to provide clinical,and pathological evidence for determining the safe surgical margin.Methods Of 109 patients,60 patients received conventional parotidectomy and 49 patients received functional regional parotidectomy.The rates of tumor recurrence and complications were compared between the groups of patients.Results There was no significant difference in the incidence of tumor recurrence,the facial paralysis and sialosyrinx between two groups.The rates of Frey's syndrome,numbness of auricular region,and facial asymmetry were 30.0％,61.7％,and 38.3％ in the patients with conventional parotidectomy respectively,while the rates were 6.1％,30.6％,and 8.2％ in the patients with functional regional parotidectomy,with significant statastically difference,respectively (P ＜ 0.05 ).Of 109 patients,33 with incomplete capsule,29 with capsule penetration,25 with pseudopodia,and 13 with satellite nodules.There was no significant difference in the depth of tumor infiltration between two groups of patients.For the tumor smaller than 2 cm,the depth of infiltration in conventional group was from 0.061 to 1.122 mm,functional group was from 0.442 to 3.127 mm (Z =- 1.093,P =0.057) ; for the tumors between 2 - 4 cm,the depth in conventional group was from 0.081 to 7.908 mm,functional group was from 0.082 to 6.632 mm ( Z =-0.214,P =0.831 ) ;for the tumor larger than 4 cm,the depth of infiltration was from 0.340 to 8.476 mm.Conclusions Compared with conventional parotidectomy,functional regional parotidectomy has good outcomes and less complications.The surgical margins of pleomorphic adenomas of the parotid gland should be determined by the size of tumor.The 1 cm-surgical margins are safe for the tumors less than 4 cm,and the tumors more than 4 cm should be treated with superficial parotidectomy.