To investigate the criteria for selecting surgical approaches for frontal and ethmoid sinus osteomas of different locations and sizes on CT imaging. Using sagittal and coronal CT images, the following lines were delineated: the F-line（a horizontal line passing nasofrontal beak）, the M-line（a vertical line passing paries medialis orbitae）, and the P-line（a vertical line passing the center of the pupil）. Classification of frontal and ethmoid sinus osteomas was based on their relationship with these lines. Appropriate surgical approaches were selected, including pure endoscopic approaches, endoscopic combined with eyebrow incision approach, and endoscopic combined with coronal incision approach. This method was applied to a single center at the Third Affiliated Hospital of Sun Yat-sen University for endoscopic resection of frontal and ethmoid sinus osteoma. Case Data: Sixteen cases of ethmoid sinus osteomas were treated from January 2020 to September 2023. Among these cases, there were 9 males and 7 females, with ages ranging from 18 to 69 years, and a median age of 48 years. Thirteen cases underwent pure endoscopic resection of the osteoma, while in three cases, a combined approach was utilized. Among the combined approach cases, two exceeded both the M-line and the F-line but did not cross the P-line; therefore, they underwent endoscopic combined with eyebrow incision approach. One case exceeded all three lines and thus underwent endoscopic combined with coronal incision. In all cases, complete resection of the osteoma was achieved as per preoperative planning, and none of the patients experienced significant postoperative complications. For frontal and ethmoid sinus osteomas, it is advisable to perform a thorough preoperative radiological assessment. Based on the size of the osteoma and its relationship to the three lines, an appropriate surgical approach should be chosen to optimize the diagnostic and treatment plan.