This study was performed on 17 female dental hygienists to find an appropriate method to reduce the hygienists' body discomfort while scaling, and provide a foundation to educate them how 10 posture during the process. To assess the arm abduction, elbow flexion, neck flexion, trunk flexion and trunk lateral bending through Video 2D(two dimensional motion) analysis and assessing the risk through the Action level of RULA(rapid upper limb assessment) checklist, an ergonomic analysis method. Correlation analyses on the posture angles and on body discomfort were performed. ANOVA analysis on scaling treatment position and the scaling treatment region of patients was also performed. The results are as following. 1. 20 analysis while scaling, arm abduction was $40{\sim}79.9^{\circ}$, elbow flexion $20{\sim}110^{\circ}$, neck flexion $50{\sim}100^{\circ}$, trunk flexion $60{\sim}80^{\circ}$, and trunk lateral bending $5{\sim}19.9^{\circ}$. 2. The Action level of RULA was 2. 3 resulted from scores 4 and 5 of group A which includes upper arm, lower ann, wrist, and scores 2 and 4 of group B which includes neck, trunk, legs. It means that the scaling treatment posture causes a high incidence rate of musculoskeletal that an additional investigation and improvement should be followed without hesitation. 3. There were significant differences among the maxilla right, maxilla anterior, maxilla left, mandible left, mandible anterior, and mandible right of a patient of the right and left upper arm, lower arm, neck, trunk, group A, group B, final RULA score while scaling treatment. 4. There were significant differences among the time position of 8, 9, 10, 11, 12, 13 of the right and left upper arm, lower arm, neck, trunk, group A, group B, final RULA score while scaling treatment, 5. As for the body discomfort, neck, right shoulder, left shoulder, right back, right wrist etc. were listed on top. As a conclusion, performing the time position of 12 which shows low right and left final RULA scores is better than the time position of 8 and 10 which show high final RULA scores to reduce the body discomfort while scaling treatment.