Objective To investigate the regular pattern of traction forces during the treatment of distal radius fracture by reduction fixator with pins. Methods A self-designed pin-lock style force transducer instead of two original pin locks in the distal of reduction fixator was adopted to conduct continuous testing on six cases of unstable distal radius fracture of forearms treated by reduction fixator in vivo. The value of static traction force and the added value of traction force in fist clenching at the postoperative 1st, 5th, 14th, 21st, 28th, 35th, 42nd, 49th day, was recorded respectively. Results The maximum and minimum static traction force was 9.93 kg and 2.26 kg, respectively, with mean value of (4.93±1.79) kg. The maximum and minimum traction force increment in fist clenching was 10.40 kg and 0.13 kg, respectively, with mean value of (3.17±2.42) kg. Conclusions Larger axial forces can be generated in muscles of the forearm, by both static tension and dynamic contraction, which might be a serious negative factor in healing unstable distal radius fractures.