The invention provides a paper mill waste pulp treatment process. The treatment process comprises the steps that 1, grinding and separation are conducted on the waste paper pulp conveyed by a conveyor belt to paper-plastic separation machine; 2, the solid-liquid mixture in a water collection tank is pumped into a multiple mold filter, short fibers are filtered out, the filtrate is fed into a circulating pond, and reutilized after the purification; 3, long fibers falling into a first sedimentation pond and the solid impurities are isolated; 4, re-isolation is conducted on long fiber and solid impurities through the feeding of isolated long fibers from step 3 and a small amount of solid impurities by a scraper conveyor into a second settling pond, and impurities are removed; 5, dewatering treatment is conducted on the long fiber isolated from step 4 and conveyed into fling drying machine, and reutilization is conducted. The paper mill waste pulp treatment process has the beneficial effect of being high in pulp recovery rate and lower in production cost, the problem of being difficult in reutilization of waste paper pulp is solved, and the efficient use of renewable resources is ensured.