【【Objective】A long-term field experiment was conducted in a typical black soil area in Northeast China to study the changes in soil colloidal phosphorus content in the 0-100 cm profile under no tillage (NT) and traditional tillage (CT). The purpose was to explore the effect of conservation tillage on the content of colloidal phosphorus and analyze the distribution pattern of colloidal phosphorus in soil under different tillage measures. 【Method】 The research area is located at the National Field Science Observation and Research Station of Hailun Farmland Ecosystem, Chinese Academy of Sciences (47°26′N, 126°38′E), where corn soybean rotation is implemented. After the corn harvest, the soil profiles of farmlands were collected and divided into eight layers: 0-5, 5-10, 10-15, 15-20, 20-40, 40-60, 60-80 and 80-100 cm. The contents of colloidal phosphorus and soil physical and chemical indicators in each soil layer were determined to study the variations and distribution patterns of colloidal phosphorus content in the 0 - 100 cm soil profile under straw mulching no-tillage (NT) and conventional tillage (CT). 【Result】NT significantly increased the content of colloidal phosphorus (P < 0.05), with an average increase of 33.40%. In the same soil layer, NT significantly increased the contents of total phosphorus and available phosphorus, and the average contents of molybdate reactive phosphorus (MRP) and molybdate ureactive phosphorus (MUP) (P < 0.05). Among them, MRP increased by 18.44% and MUP increased by 49.19%, but NT significantly decreased the proportion of MRP in colloidal phosphorus in the surface soil by 12.21% (P < 0.05). TPcoll and colloidal MRP were mainly carried by fine particles of 1-220 nm. The average proportion of FPcoll (1 - 220 nm colloidal phosphorus) in each soil layer under NT treatment was 73.47%, and that under CT treatment was 74.34%. The proportion of FMRP (1-220 nm MRP) was 59.64% under NT treatment and 63.22% under CT treatment, and the average proportion of FMRP in the surface soil under NT treatment was 5.66% lower than that under CT treatment. The content of colloidal phosphorus was affected by soil physical and chemical properties, showing a significant negative correlation with bulk density and a significant positive correlation with field capacity, soil porosity, total phosphorus content, available phosphorus, total carbon, and total nitrogen. 【Conclusion】 In conclusion, conservation tillage generally increases the contents of colloidal phosphorus, total phosphorus, and available phosphorus in each soil layer. This change might be due to the influence of NT on soil physical and chemical properties, and the increase in colloidal phosphorus content might increase the risk of phosphorus loss.