The invention discloses a pulverized coal accumulation prevention fixing shrinkage cavity device with horizontally-arranged primary air pipes for a boiler coal pulverizing system. The device comprises the horizontally-installed primary pulverized coal air pipes and fixing shrinkage cavities formed in the primary pulverized coal air pipes. The two sides of the lower end of each fixing shrinkage cavity are provided with slope-shaped pulverized coal accumulation prevention devices inclined downwards gradually to the two sides. The horizontally-installed pulverized coal accumulation prevention fixing shrinkage cavity device has the advantages that pulverized coal accumulation is prevented, and when existing, the pulverized coal will slip off along the slopes to be prevented from accumulating; the device has a throttling effect, and the speeds of the primary air pipes of a same-layer burner can be controlled to be uniform; after the pulverized coal accumulation prevention fixing shrinkage cavity device is horizontally installed, it is unnecessary to conduct a leveling test on the primary air pipes; the risk that pulverized coal accumulates on the upper portions of the horizontally-formed fixing shrinkage cavities and smolders to explode can be avoided; the horizontally-installed pulverized coal accumulation prevention fixing shrinkage cavity device has wear resistance.