A new approach, which combines the radar’s dynamic information and several scans’ measurements to deal with the data initial association problem in high clutter environment of tracking-while-scanning systems, is proposed. First, the dynamic initial track numbers are estimated by using the measurements’ number in the sliding window, the target detection probability and the receiver’s noise sampling information. Then the estimated initial track numbers are adopted to adjust the initial correlation region and the normalized residual square threshold adaptively. Therefore, lots of false initial trajectories are suppressed. Simulation results demonstrate that our approach can solve the real time data initial association problem better than logic-based method.