The purpose of this study was to investigate the effects of stance configuration and dumbbell load on knee kinetics in squat. Ten weight lifting athletes with average age of 21 years old were participated in this study. Vicon motion analysis system and Kistler force plate were used to analyze the three-dimensional knee joint forces and moments in two load conditions, body weight and dumbbell. In addition four stance widths, including narrow stance, narrow stance & toe out, medium stance & toe out and wide stance & toe out were also used in this study. Two-way analysis of variance with repeated measures was used to compare the kinetic differences between different stance configurations and dumbbell loads. If statistical analysis reached significance on the main effect, LSD method was used for further post hoc analysis. The results showed that medial force, compression and external rotation moment in the knee joint were affected by stance configuration. Knee joint force during squat was found to be posterior force. Wide stance & toe out showed a lesser medial force and external rotation moment but a higher compression. Moreover, the use of dumbbell in squat increased the posterior force, compression and extension moment. Dumbbell squat was an effective exercise for quadriceps strengthening but it should be cautious for the higher compression and posterior shear force. This study concluded that knee joint force and moment during squat would be substantially affected by stance configuration and the use of dumbbell. These findings could be served as useful biomechanical guidelines for those, who use squat for muscle strengthening or rehabilitative treatment.