Abstract： Objective:Cone beam computed tomography(CBCT)was used to measure the mesiodistal angulation of maxillary molars in patients with skeletal classⅡ malocclusion, and to analyze the influence of maxillary third molars on the mesiodistal angulation of maxillary molars.Methods:This study was a case control study, from June 2018 to September 2022, a total of 87 patients(31 males and 56 females)with skeletal class Ⅱmalocclusion, aged(25.45±4.75)years old and ranging from 25 to 45 years old, were collected from the department of Stomatology of the General Hospital of Northern Theater Command.Invivo 5.0 software was used to measure the mesiodistal angulation between U6, U7 and the palatal plane and the FH plane under the conditions of different maxillary third molar impaction and mandibular plane angle and posterior anterior height ratio.Results:All patients were divided into normal eruption group, high impaction group and congenital absence group according to the impaction of maxillary third molar.When the palatal plane was used as the reference plane, the angle of U6 between the normal eruption group[(95.85±7.12)°]and the high impaction group[(101.29±3.07)°], the angle of U7 between the normal eruption group[(106.29±6.74)°]and the high impaction group[(113.60±3.88)°], and the angle of U7 between the high impaction group and the congenital absence group[(106.49±8.01)°], the differences were statistically significant( P<0.05).When the FH plane was used as the reference plane, the angle of U6 was compared between the normal eruption group[(95.03±6.17)°]and the high impaction group[(98.17±5.01)°], and the angle of U7 was compared between the high impaction group and the congenital absence group[(104.83±5.82)°], the differences were statistically significant( P<0.05).All patients were divided into low angle group, average angle group and high angle group according to mandibular plane angle and posterior anterior height ratio.When the palatal plane was used as the reference plane, there were significant differences in the angle of U6 between the high angle group[(101.00±4.65)°]and the average angle group[(98.17±6.13)°], the angle of U6 between the high angle group and the low angle group[(91.21±5.46)°], the angle of U6 between the average angle group and the low angle group, the angle of U6 between the high angle group[(111.29±5.46)°]and the average angle group[(107.28±8.20)°], the angle of U7 between the high angle group and the low angle group[(103.08±6.41)°], the angle of U7 between the average angle group and the low angle group, the differences were statistically significant( P<0.05). Conclusions:The high impaction of maxillary third molar makes the long axis of U7 distally inclined, and U6 also has a trend of distally inclined.