The invention discloses a combustion chamber of a high-speed diesel engine. The combustion chamber is cylindrically arranged at the end part of a piston rod, and the combustion chamber is characterized in that the combustion chamber sequentially comprises an inward contraction port, a throat port, a bottom groove and a boss from the top end of the piston rod to the bottom of the combustion chamber, wherein the inward contraction port is of an annular arc-shaped groove with the inner diameter which is gradually reduced from the top end of the piston rod, the throat port is of an annular arc-shaped bulge connected to the bottom edge of the inward contraction port, the bottom groove is of an arc-shaped groove arranged on the edge at the bottom of the combustion chamber, the inner diameter of the throat port is smaller than those of the inward contraction port and the bottom groove, the boss is of a spherical crown-like structure arranged at the center of the bottom of the combustion chamber, a diversion table is arranged between the bottom edge of the boss and the lower edge of the bottom groove, and the diversion table is of an annular arc-shaped raised structure. The combustion chamber disclosed by the invention can be used for preventing a high-pressure injected oil beam from being subjected to a wall impingement phenomenon, improving the fuel oil spatial distribution and oil-gas mixing uniformity, and further ensuring that the engine is higher in thermal efficiency and lower uin oil consumption and emission.