To solve the problem that the duration is too long when the change of the measuring process data of industrial real-time database appears slow, the double compression algorithm with linear interpolation of dynamic threshold is advanced. Good compression quality and reduction effect of process data is accessed. The compression and fitting times are less than 1ms, and the compression ratio is 6:1 on the 6000 real-time data compression. The compression time is short, and the compression ratio is high. The fitting error between each fitted value and the original value is within the threshold 1.0. The comprehensive performance is better than SLIM and Swinging Door compression algorithm.