Abstract: 【OBJECTIVE】The research investigated the effects of long-term fertilization on enzyme activities and soil fertility for the black farmlands under different soil matter levels.【METHOD】In this study, the research objects are black soils under five different organic matter levels (Lishu(SOM1.7), Dehui(SOM3), Helen(SOM5), Nenjing(SOM6), Bei'an(SOM11)), it analyzed the soil enzyme activities such as urease, phosphatase, protease, invertase and the contents of soil organic matter, total nitrogen, total phosphorus and alkaline hydrolysis nitrogen, available phosphorus.【RESUITS】The results showed that, the application of chemical fertilizers can increase the nutrient content and soil enzyme activities of black soil. Bei'an (SOM11) increase in maximum, reached significant difference level between it and other four soils (p<0.05). The results of correlation analysis showed that soil urease, phosphatase, protease, invertase and soil organic matter, total nitrogen, total phosphorus, available nitrogen are significantly related, soil urease, invertase can reflect the quality change trend of the soil under different organic matter levels after long-term fertilization.