In order to evaluate the improvement effect of biochar addition on soil physical and chemical properties, humus and humification degree, a field experiment was conducted based on biochar application. Four treatments were set up: blank control (CK), conventional fertilization (NPK), biochar application alone (B1) and biochar combined with fertilizer (NPK+B1). Through two consecutive years of field experiments, the effects of biochar addition on soil physical and chemical properties, humic acid (HA), fulvic acid (FA) and humin (HM) as well as soybean yield were studied. The results showed that biochar application could effectively improve soil nutrients in a short period of time, increase soil humus content, improve soil stability, improve soil texture and increase soybean yield. Compared with CK, B1 and NPK+B1 treatments had more obvious improvement effects on soil physical and chemical properties, with electrical conductivity (EC) increased by 3.50%-98.99%, organic carbon (OC) content increased by 18.01%-23.18%, alkali-hydrolyzed nitrogen (AN) content increased by 23.48%-37.15%, total nitrogen (TN) content increased by 14.93%-25.37%, available phosphorus (AP) content increased by 8.33%-110.16%, total phosphorus (TP) content increased by 10.00%-45.00%, available potassium (AK) content increased by 6.61%-20.76%, total potassium (TK) content increased by 13.24%-30.74%, and soybean yield increased by 54.34%-90.36%. Compared with NPK treatment, the contents of HA, FA and HM in NPK+B1 treatment were increased by 38.62%, 26.76% and 16.45%, respectively. And through correlation analysis and principal component analysis, it was shown that soil pH, electrical conductivity, available potassium, total potassium, total phosphorus, alkali-hydrolyzed nitrogen, total nitrogen, organic carbon and soybean yield were significantly positively correlated with humic substances. Therefore, chemical fertilizer combined with biochar treatment can effectively improve soil physical and chemical properties, increase soil humic substance content, and provide theoretical and technical support for overcoming soybean continuous cropping obstacles and improving soybean productivity.