The utility model discloses a secondary trough-type liquid distributor with a steady flow plate, which comprises a main groove, a branch groove and a liquid feed pipe, wherein lower part side wall holes are uniformly formed in both sides of the branch groove; two sides of the steady flow plate are fixedly connected to middle positions on two inner sides of the main groove; overflow orifices are uniformly formed in the bottom of the steady flow plate. As the perforated steady flow plate is arranged in the main groove, the lowering kinetic energy of the liquid can be buffered properly. Therefore, the problems that a liquid distributor is damaged by impact, the liquid level of liquid in the main groove fluctuates rapidly, the liquid surface gradient is high, and feed liquid splashes are solved; the uniformity of liquid distribution is improved effectively; the mass transfer efficiency during the separation process is improved.