The invention discloses full-degradable oil field seepage-proof cloth and a preparation method and an application thereof, and belongs to the field of the oil field waste liquid recovery. The full-degradable oil field seepage-proof cloth comprises a support layer and a seepage-proof layer, wherein the support layer is degradable heat-sealing non-woven fabric, melt-blowing non-woven fabric, spunlace non-woven fabric, loop bonding non-woven fabric, wet non-woven fabric, pulp air laid non-woven fabric, spunbond non-woven fabric, or needling non-woven fabric; and the seepage-proof layer is a degradable seepage-proof membrane. The degradable non-woven fabric is set as the support layer, and the degradable seepage-proof membrane is set as the seepage-proof layer, the seepage-proof cloth is endowed with excellent seepage-proof performance, degradable performance and mechanical property, thereby well repair waste liquid is conveniently collected, and the well repair waste liquid is prevented from seeping. The seepage-proof cloth is completely degraded in a later period, and secondary pollution is prevented from being caused.