The invention discloses a back pressure sealing element for a metering pump. The back pressure sealing element for the metering pump comprises a shaft sleeve, a fastening ring, a limiting ring, a static ring and a dynamic ring. The back pressure sealing element for the metering pump is characterized in that an installation groove is formed in the shaft sleeve, the fastening ring is connected with the shaft sleeve, a sealing ring is arranged between the shaft sleeve and the fastening ring, the limiting ring is connected with the shaft sleeve through a connecting screw rod, a sealing ring is arranged between the limiting ring and the connecting screw rod, one end of the static ring is connected with the limiting ring, the static ring is provided with a limiting groove and the sealing ring, and a stretch ring is arranged on the dynamic ring. According to the back pressure sealing element for the metering pump, the stretch ring is arranged on the dynamic ring, the limiting groove is formed in the static ring, the stretch ring is arranged in the limiting groove, and therefore not only the phenomena that due to the high pressure of the metering pump, the static ring and the dynamic ring bounce off each other and leakage of the metering pump is caused are avoided, but also the quality performance of the back pressure sealing element is improved. Through a buffer block between the dynamic ring and the static ring, the impact force exerted by the dynamic ring on the static ring can be lowered, the damage to the back pressure sealing element is reduced, and therefore the service life of the back pressure sealing element is prolonged.