Rice production in India is an important part of the national economy. The use of modern agricultural tools and equipment for paddy threshing are limited to the plain land of India, whereas, traditional methods are still prevalent in most of the parts of the North-East hilly region. Farmer of this region faces substantial difficulties in adoption of modern tools and equipment due to mismatch of the design according to their requirement, lacking portability features, socioeconomic status etc. Therefore, the present study made an attempt to evaluate and improve the existing pedal operated paddy thresher in the digital environment, using digital human models, for the prevention of work-related musculoskeletal disorders. The various postural score of body part obtained from a well-known and validated posture analysis tool called rapid upper limb assessment technique was used for ergonomic design improvement using response surface methodology. Results obtained from the assessment reveals that optimum design height of pedal thresher suitable for 5th to 95th percentile workers of the North-East population was found to be 81 cm with the trunk score of 2.005.