Abstract: Low back pain (LBP) is a health problem that is often experienced by farmers due to lifting activities, bending over a relatively long time, and carrying loads with an unergonomic attitude. One of the efforts to deal with the problem of low back pain is ergonomics intervention through the William Flexion Exercise method. This study aims to determine the effect of William Flexion exercise on reducing low back pain. This research is a quasi-experimental study with one group pre test post test design. William flexion exercise is given in the form of abdominal strengthening movements with a duration of 30-40 minutes. The research sample consisted of 23 people determined by random sampling technique from a population of rice farmers in Lembor Selatan District, West Manggarai Regency. The measurement of LBP levels using the Oswestry questionnaire was carried out before and after the intervention. Data differences before and after the intervention were tested using the Wilcoxon sign rank test. The results showed that William Flexion exercise can reduce low back pain of farmers from an average score of 64.26 to 47.96 or a decrease of 25.36% with p = 0.000. The conclusion of this research is william flexion exercise can reduce Low back pain.