Abstract: The present invention discloses a deep soil water percolation monitor and a monitoring method therefor. The monitor includes a soil water balance portion, a flow collection portion, a measurement portion, a water collection portion, a rainfall collecting portion and a control device, wherein the control device includes a central controller, a water inlet pipe, a plugging trough, a drive mechanism, a water level sensor and a humidity sensor. The monitor and monitoring method provided by the present invention can increase the measurement sensitivity of the percolation monitor and increase the measurement accuracy.