The invention discloses a system and a method for measuring the amount of rainfall infiltration in soil, and a construction method. The system comprises a cavity arranged between ground surface and underground water level, and soil in a natural state is arranged on the top and at the bottom of the cavity; the cavity is internally provided with a soil infiltration amount measurement device, and the soil infiltration amount measurement device comprises a collection funnel, a metering device and a base which are sequentially connected from top to bottom; a support layer and a water-permeable filtering layer sequentially covers an opening formed in the top of the collection funnel; the upper part of the water-permeable filtering layer is in close contact with the soil; the metering device is connected with a data storage device arranged on the ground. The measuring results of the system and the method reflect the change of the amount of rainfall infiltration in the soil in a natural state. A plurality of cavity parts can be buried in different sections and different depths according to concrete requirements, so that a plurality of places can be monitored at the same time for a long period. The system and the method are not limited to the specific conditions and are suitable for any geographical environment or lithologic condition, thus having good universality.