Osteoarthritis is the most common form of arthritis in the knee. It is occurring when the protective cartilage that cushions the ends of your bones wears down over time and mostly often in people 50 years of age and older. The study was designed to randomized control trial and aimed to compare before and after the 3-months intervention program on self-care sandbag exercise program for knee osteoarthritis patients in the secondary care in Thailand. They were divided into 2 groups, the intervention group, and the control group by using the probability sampling. Seventy knee osteoarthritis patients participated in this study. Both of group were assessed the Oxford knee score and the knowledge of knee osteoarthritis at the baseline and after 3-months intervention program. The Independent t-test and Paired sample t-test were used for comparison the all parameters between and within the group, respectively. The results showed that the Oxford pain score of knee osteoarthritis was decreased scientifically more than the control group (p<0.001) and the knowledge of knee osteoarthritis was increased significantly (p<0.001). In conclusion, the self-care sandbag exercise program can reduce the severity of pain among knee osteoarthritis patients and can promote to the usaul care for the osteoarthritis pateintes.