Abstract: This research aimed to study the effect of training on activities in organic farm of farmers in Mahasarakham province Thailand and to comparing their knowledge after training. The sample composed of 38 farmers in Namthaieng village, Kosumpisai district, Mahasarakarm province which have been selected by a purposive sampling technique. The research design was just one group pre-and post-test. The data collection was analyzed by mean, standard deviation and testing hypothesis by t-test. The study results showed that total knowledge on activities in organic farm of farmers in Mahasarakham province was at the high level. The farmers had knowledge on knowledge on activities in organic farm after training was rated higher that before training (p<0.05).