The invention relates to a self-pumping fluid-dynamic-pressure-type mechanical seal. More than three groups of backwards-bent-type fluid grooves are formed in the moving ring seal end surface of the self-pumping fluid-dynamic-pressure-type mechanical seal, wherein each fluid groove is composed of a slope groove and a horizontal groove, the outlet of each fluid groove is located outside the moving ring seal end surface, and the inlet of each fluid groove is located in the middle of the moving ring seal end surface, and is communicated with a sealing cavity through an axial hole passage or an axial and radial combined hole passage on a moving ring. When the moving ring rotates, media in each fluid groove are accelerated to be high-speed fluid, the high-speed fluid flows to the outer diameter side of the moving ring and is pumped into the sealing cavity under the action of centrifugal force and forms a low-pressure area in the inlet of each backwards-bent-type fluid groove, and media in the sealing cavity flow into each backwards-bent-type fluid groove through the axial hole passage or the axial and radial combined hole passage under the action of pressure difference, wherein the axial hole passage or the axial and radial combined hole passage is arranged on the moving ring, and is communicated with the sealing cavity so as to form a new self-pumping cycle. In the process that the high-speed fluid is pumped out, the flowing speed is reduced, the pressure is increased, and certain opening force is formed as the circulating sectional area gradually increases. The self-pumping fluid-dynamic-pressure-type mechanical seal has good self-lubricating, self-washing and anti-solid-particle-interference ability and superior sealing performance.