【Objective】With developing agriculture, the amount of crop residues increases, too, posing a serious environmental concern of how to rationally utilize the by-product. Incorporation of crop residue into the field is one of the optimal ways to recycle crop residue. In Northeast China, straw is returned into the field normally in two ways. One is to plow the returned straw into soil, and the other leave the straw over on the surface of the field as mulch. However, the traditional ways do have some shortcomings, for instance, the returned straw is hard to decompose in the soil; it affects seedling emergence; it makes tillage difficult, and so on. Consequently a now straw returning method is, hereby, invented, that is, even incorporation of straw (EIS), which is implemented in two steps, 1) straw is crashed into pieces, 1~2 cm in length and spread over the field by the combine harvesting the crop; and 2) the straw is plowed evenly into the 0~70 cm soil layer, using the crashing-ridging technology. When the new method is applied, the soil pan is tilled loose, thus reducing the soil bulk density, and improving the soil structure. However, so far little has been done on effects of this new straw incorporation method on soil physico-chemical properties and maize yields. Therefore, in this study, a field experiment was carried out to evaluate effects of EIS on soil physico-chemical properties and maize yields by comparing EIS with other straw returning modes or methods.【Method】The field experiment, laid out in a mono-cropping maize field of chernozem soil in the Zhengbang Farm of Nong'an County, Jilin Province, was designed to have four treatments, i.e. Treatment CK (no straw returned), Treatment SM (straw returned as mulch), Treatment EIS (straw incorporated evenly into the soil using the crashing-ridging technique) and Treatment SP (straw plowed into the soil). Soil bulk density was determined plot by plot using the cutting ring method, and soil compactness, too, with a soil compactness meter; soil aggregates composition analyzed with the dry-sieving and wet-sieving methods; and fulvic acid (FA) and humic acid (HA) extracted with the modified humus component extraction method for analysis of structure with the Fourier transform infrared spectroscopy. Besides, maize yields of the treatments were calculated.【Result】Compared with CK, Treatment EIS and Treatment SP significantly reduced soil bulk density by 33.11% and 28.38%, respectively, and Treatment SM did only by 12.16%, and similar trends were found in terms of effects on soil compactness. As for content of ＞0.25 mm water-stable soil aggregates, Treatment EIS was 16.71%, 13.18% and 24.29% higher than Treatment CK, SP and SM, respectively. However, all the straw returning treatments increased mean weight diameter (MWD) and water stability coefficient (K), as compared with CK. Treatment EIS, SP and SM was 80.28%, 61.69% and 47.04% higher than Treatment CK in MWD, and 33.69%, 23.71% and 11.40% higher in K. Moreover, Treatment EIS, SP and SM increased soil organic carbon content in the surface soil layer by 27.8%, 15.9% and 7.5%, respectively. Meanwhile, Treatment EIS significantly increased the content of soil humus substances (HEC), soil humic acid carbon (HAC) and fulvic acid (FAC) by 47.6%, 63.3% and 33.8%, respectively, as compared with CK. Among all the straw returning treatments, Treatment EIS was the most significant in effect of increasing the content of HEC, HAC and FAC, being, 28.2%, 26.3% and 30.4%, respectively, higher than Treatment SP and 8.2%, 12.1% and 4.3%, respectively, higher than Treatment SM. Treatments EIS and SP increased soil HAC/FAC, too, being 25% and 21.6% than CK. Moreover, Treatment EIS altered the composition of humus more significantly than all the other treatments, by increasing the proportion of alkyl C and the ratio of aliphatic C/aromatic C, but Treatment SP was relatively higher than Treatment EIS in effect of raising the content of aromatic C.【Conclusion】All the findings in this experiment demonstrate that straw returning decreased soil bulk density and soil compactness, accelerated the accumulation of soil organic C and various components of humus, significantly changed the content of ＞0.25 mm soil water-stable aggregates and the values of mean weight diameter (MWD) and K, improved the structure of soil HA and increased maize yield, with the practice of EIS (even incorporation of straw) in particular, which suggests that the practice of EIS might be an ideal straw returning method to improve physico-chemical properties of the soil and maize yield.