The invention discloses a portable initial rainwater collecting and purifying water seeping device, and mainly relates to a water seeping device. The portable initial rainwater collecting and purifying water seeping device comprises a strainer, a seeping tube, a collecting and purifying bag, a filtering and reverse-filtering outer layer, a base and a foundation pit, wherein the foundation pit is arranged under the ground; an inner layer formed by water-pervious fillings is arranged on the inner surface of the foundation pit; the seeping tube is arranged in the inner layer of the foundation pit; the inner surface of the seeping tube is provided with the collecting and purifying bag; the outer surface of the seeping tube is provided with the filtering and reverse-filtering outer layer; seeping holes are formed in the seeping tube; the bottom of the seeping tube is provided with the base; seat holes are formed in the base; a strainer frame is arranged at an upper end opening of the foundation pit; the strainer is arranged in the strainer frame; and strainer holes are formed in the strainer. The portable initial rainwater collecting and purifying water seeping device solves the problems of an existing product that oil stain of the initial rainwater cannot be adsorbed; residue cannot be accumulated or stored; and the rain seepage and the underground water supplementation cannot be realized.