A combustion chamber of diesel engine. The diesel engine includes a cylinder head, a cylinder sleeve, and a piston. The cylinder head, the cylinder sleeve, and the piston form the combustion chamber. The combustion chamber includes a headspace; a central part; and a collision belt. The collision belt includes a collision surface, an upper guide surface, and a lower guide surface. The collision belt is configured to connect the headspace and the central part. The collision surface is an inclined surface, a convex surface, or a concave surface. The first tapered surface includes a second inclined surface, a second curved surface, and a third inclined surface; the second tapered surface includes a fourth inclined surface, a third curved surface, and a second concave surface; the first curved surface includes a second convex surface and a third concave surface.