Tai Chi (TC) shows some beneficial effects in reducing pain in knee osteoarthritis (OA). However, the selection of criteria TC forms in previous studies were unclear and inconsistent, possibly accounting for the varying outcomes and rendering the training effects suboptimal. We have selected four optimal TC (OTC) forms based on the knee joint load and its association with pain. This pilot study sought to examine the effect of the OTC forms on reducing knee pain in individuals with knee OA. Fifteen knee OA participants were recruited. Their knee joint pain level was rated by using the Visual Analogue Scale before and after two weeks of OTC training and compared between these two assessments. The two-week OTC training course was well accepted by our participants. The knee OA pain showed a significant reduction (median pain score: 5 ​cm before training and 1 ​cm post-training, Wilcoxon p ​< ​0.001) after the two-week training program. Our pilot results revealed that the 2-week four-form-based OTC program could significantly reduce the knee pain level in people with knee OA. Additionally, our OTC program appears to be about 50% more effective in reducing knee pain than the existing TC-based program, which uses 10 ​TC forms over 12 weeks (1.59 vs. 1.06 in Hedge's g). The findings in this study may inform the development of OTC-based knee pain reduction programs and the design of relevant clinical trials to establish OTC's effectiveness, safety, and dose-response relationship in easing knee OA pain.