The invention relates to an easy-to-assemble static pressure outflow developing nozzle which comprises a main body, a partition plate and a cover plate, wherein the main body is long strip-shaped, the middle part of the top surface of the main body is downwardly concave to form a primary flow channel, the middle part of the bottom surface of the primary flow channel is downwardly concave to form a secondary flow channel, a vertical flow guide blind hole is downwardly formed in a position at one end of the bottom surface of the primary flow channel, an exhaust interface and a liquid inlet interface are correspondingly formed in positions on the upper side and the lower side of one end surface of the main body, first and second diversion flow channels are correspondingly formed between the exhaust interface and the first flow channel and between the liquid inlet interface and the lower end of the vertical flow guide blind hole; the mouth edge of the secondary flow channel is arranged to be a diversion inclined surface, and a plurality of small outflow holes are formed in the bottom of the secondary flow channel; the partition plate is arranged at the mouth part of the secondary flow channel in the main body, and an overflowing seam is formed above the diversion inclined surface on the partition plate; the cover plate is hermetically assembled at the mouth part of the primary flow channel. The developing nozzle has the benefits of uniform sand stable spraying, low impact, compact structure and easiness in processing and assembly.