Currently radar data transmission mainly depends on the short-wave radio and fiber-based communications, thus the destruction of the means of transmission will greatly reduce the capacity of communication. To solve the problem of track data transmission at low data transmission capacity, we proposed a data compression method based on track data curve fitting. Target detected by radar was taken as trace point, then the trace points were associated to form a track. Curve fitting was made to the track to obtain the parameters of the fitted curve. Then, the parameters of the fitted curve were transmitted instead of the track data. Finally, the parameters of the fitted curve were used to recover the track, which could greatly compress the data traffic, and implement radar track data transmission under the condition of low transmission capacity.