Field experiment was carried out to study the improvement effect of coal humic acid on soda saline-alkali soil with maize planting in Daqing.Six treatments were set up, including control (CK), single application of chemical fertilizer (T1), low amount of humic acid (T2), medium amount of humic acid (T3), high amount of humic acid (T4), low chemical fertilizer and low level of humic acid (T5).The results showed that soil pH and alkalinity decreased with the increase of humic acid application.The lowest soil pH and exchange sodium percentage were obtained in T4 treatment, which was 20.9% and 41% lower than those of CK.Soil organic matter and cation exchange capacity increased with the increase of humic acid application.The highest contents of soil organic matter and cation exchange capacity were obtained in T4 treatment, which was 100% and 28% higher than those of CK.Soil alkali hydrolyzable nitrogen, available phosphorus and available potassium increased with the increase of humic acid application.Compared with CK, the available phosphorus ，alkali hydrolyzable nitrogen and available potassium content of T4 were increased by 93.4%，19.3% and 18.7%, respectively.Soil alkali hydrolyzable nitrogen, available phosphorus and available potassium content of T5 were the highest, which were respectively increased by 23.8%, 2 times and 42.1% compared with CK.Soil exchangeable calcium and magnesium increased with the increase of humic acid application.Soil exchangeable calcium and magnesium of T4 had the highest content, which were 10.1% and 49.6% higher than those of CK.It can be seen that application of coal humic acid can reduce saline-alkali soil characteristics and improve soil fertility.The effect of humic acid combined with chemical fertilizer is more obvious.