Abstract: 【Abstract】Objective To collect the cephalometrical films of Chengdu’s healthy young adults and measure their Monson’s spherical radius. Methods Sixty healthy young adults （30 males and 30 females，aged 18 to 28 years）were collected and filmed. INFINITT software were applied to fixing the points, tracing and measurement of the cephalometrical films. Using the SPSS17.0 software package for statistical analysis. Results The Monson’s spherical radius to an average of 86.28 mm, less than the theoretical value of 101.60 mm with significant difference (P < 0.01); There was no significant difference between male and female sphere radius. Futhermore there is a correlation between the Spherical radius and SN distance ,correlation coefficient r = 0.694. Conclusions The Monson’s spherical radius of the Chengdu’s healthy young adults and the theoretical value have significant differences, the surveys of different regions also have significant difference, it is necessary to set up databases for chengdu area, as the occlusal recording parameters for the dental hospitals and clinics and a reference of orthodontic treatment.

Key words: Monson’s sphere, occlusion, jaw measurement