Scroll profile plays a key role in dynamic property of the machine. The scroll profiles were constructed by using normal-equidistant-line method based on baseline with the first-order function of radius of curvature in accordance with continuity conditions. The models of suction chamber, compressing chamber and discharge chamber were established based on the parameters of the baseline. The dynamic process of dynamic gas forces in a scroll compressor verse crank angle was obtained. The influence of the first-order curvature radius parameters on dynamic property was approached. The numerical simulation showed that the first-order curvature radius parameters of top scroll profile had significant effects on dynamic property of a scroll machine. Furthermore, the discontinuity of curvature radius of connecting point on the top first-order and involutes led to fluctuation and polarity change of radial force. Thus, the sealing forceload of radial clearance, leakage loss and bearing life would be influenced directly. 