The invention discloses a high-compression-ratio four-cylinder gasoline engine catalyst tight coupling type exhaust system which comprises four exhaust manifolds, a first joint manifold, a second joint manifold, an exhaust header pipe and a three-way catalyst. The three-way catalyst is arranged in the middle of the two joint manifolds. The three-way catalyst divides each joint manifold into an upper part and a lower part. At least one vertical partition plate is arranged inside the three-way catalyst. The three-way catalyst is vertically divided into a first gas cavity and a second gas cavity through the vertical partition plate. The first gas cavity is communicated with the upper part and the lower part of the first joint manifold. The second gas cavity is communicated with the upper part and the lower part of the second joint manifold. After the structure is adopted, the compression ratio of a gasoline engine can be increased, the heat efficiency is improved, the occupied space of the exhaust system is reduced, and the high-compression-ratio four-cylinder gasoline engine catalyst tight coupling type exhaust system is suitable for space arrangement of a small-displacement engine, the temperature of a catalytic agent inside the three-way catalyst can be increased, the problem that emission is high during cold starting is reduced, exhaust interference can be reduced, and exhaust back pressure is decreased.