Abstract: Through farmland soil compaction simulation device，matric potential as indicators of soil compaction， compaction effect of typical black soil region of northeast black soil in 0.1~2.5 s action time were studied.Results showed that black soil in 100，200，400 and 800 kPa ground pressure and during 0.1~2.5 s action time had threshold time of excessive compaction.Threshold time can be determined by the relationship of soil matric potential and action time.With the increase of soil organic matter，threshold time improved.Therefore，in the precondition of ensuring the operation quality，reasonable selection of implement action time，reducing ground pressure and increasing organic matter content were important measures that avoid excessive compaction of soil.