［Objective］This study aimed to study the effects of different tillage practices on the growth and development of soybean root system，the rate of root secretion，and soil physicochemical properties in the black soil region of Songnen Plain，and to clarify the differential transmission processes by which tillage practices influence crop yield through changing soil physicochemical properties and root characteristics.［Methods］A soybean variety from the northeast black soil region was used as the test materials. Four tillage treatments， including no-tillage straw mulch（NTS），no-tillage（NT），deep tillage（DT）and conventional tillage（CK）， were set. Their effects on soil physicochemical properties，soybean root morphology，and crop yield were studied. ［Results］1）NTS and DT increased soil nitrogen and phosphorus levels by exogenous straw incorporation. Compared with CK，inorganic nitrogen and available phosphorus were increased by 35.8% and 26.3% under NTS，and by 42.1% and 33.7% under DT，respectively. 2） Soil nutrient level and compactness jointly determined soybean root morphological characteristics. The direct influence of soil compactness on root morphology（path coefficient was 0.89）was greater than that of soil nutrient（path coefficient was 0.86）. Compared with CK，NTS promoted the growth and development of soybean roots under high nutrient availability and high soil compactness，NT inhibited the growth and development of soybean roots under low nutrient availability and high soil compactness，while DT promoted the growth and development of soybean roots under high nutrient availability and low soil compactness. 3）Without fertilizer application，the rate of root secretion was significantly positively correlated with root length and surface area，but significantly negatively correlated with soil nutrient concentration. 4）The explanation effect of tillage practice on soybean quality was 81%. Compared with CK，the yields under NTS，NT and DT increased by 24.7%，14.8% and 36.2%，respectively.［Conclusion］ NTS can ensure yield while reducing tillage，improving soil resistance，and promoting the recovery and retention of soil available nutrients.