Abstract:Located in the east of Heilongjiang Province, the Sanjiang Plain is an alluvial low plain formed by the confluence of Heilongjiang River, Songhuajiang River and Wusulijiang River, and covers a total area of 108 900km2, with 3 667 700 hm2 of cultivated area, in which the low-lying wet cultivated land accounts for 63.7%. The low-lying wet cultivated land generally features heavy soil and frequent waterlogging disaster, resulting in dramatic production reduction. In the harvest season, the soil is too wet to cause machinery operation unavailable, resulting in generally "high yield not bumper harvest". Which due to the following three reasons. First, the drying and wetting alternation process of soil after the water falls is slow and it is difficult to form a plough pan due to heavy clay soil, poor drainage property of soil body, and imperfect drainage channel system. The entire soil body is soft and sticky and has a low mechanical bearing capacity, which is bad for field drying and meanwhile impacts the mechanical harvest, and other operations, causing rice mildewed and snow-clad in the field, and other secondary disasters; second, the soil is in the reducing condition for a long term, so it easily generates hydrogen sulfide, and other poisoning substances to harm the rice root system; third, such kind of soil organic matters are generally 50g/kg above, so at the early stage, the soil is cold and stiffen, and the seedlings don't spring up. While at the middle and late growth stage, lodging is always caused to reduce production due to excessive soil nitrogen supply along with the decomposition of soil organic matters. It is extremely urgent to improve the issue of stagnant water in the low-lying wet soil. We took the boggy soil in the Sanjiang Plain as the test soil, and conducted field comparison experiment including the rotary tillage, deep scaification, deep plowing, mouse hole four treatments in 2017 and 2018, and studied the improvement effect of different mechanical soil preparation methods on physical and chemical properties and rice yield of the low-lying paddy field. The results show that the mechanical soil preparation methods of deep scarification and deep plowing can achieve the following: the soil water cut in 0-30 cm soil layer reduces by 10.03%-27.23%, the soil drainage property improves, the soil volume weight increase by 0.05-0.18 g/cm3, increasing degree is 6.60%-16.98%, the hardness rises, and the total pore space decrease by 3.16%-11.92%. While the mouse-hole effect is not obvious; after water drainage and field drying, the soil temperature rises significantly on an average of 1-2 ℃ every day. The effect of deep scarification is better than that of deep plowing, and the nitrogen supply intensity increases; the rice production by deep scarification increases year on year, achieving a significant level, namely, increasing by 4.21% in the 1st year and 10.46% in the 2nd year. While deep plowing generates no impact on the rice production, the rice production shows an increase trend in the 2nd year but the effect is not obvious. As for the mouse-hole, the rice production and contrast ratio in the 1st year and the 2nd year show no significant difference. So the new improvement and discussion is required on the mouse-hole soil improvement technology and machinery research & development.