In order to explore the feasibility of replacing nonrenewable peat with corn straw in traditional substrate, the cucumber varieties “Zhongnong 19” was used as the test material, and cornstalk, peat, biogas residue, vermiculite, perlite and so on were mixed according to different volume ratios to make seedling substrate. The morphology and element composition of straw and peat were analyzed and compared by electron microscope scanning and energy spectrum analysis, the effects of corn straw on the physicochemical properties of substrate and the growth of cucumber plug seedlings were investigated. Furthermore, a suitable compound substrate formula for cucumber seedling production was screened out. Twelve different substrates were tested, including a mixture of 25% peat, 25% biogas residue, 25% vermiculite and 25% perlite (CK1);100% corn straw (CK2);100% soil (CK3);a mixture of 10% corn straw, 20% peat, 20% biogas residue, 25% vermiculite and 25% perlite (T1);a mixture of 20% corn straw, 15% peat, 15% biogas residue, 25% vermiculite and 25% perlite (T2);a mixture of 30% corn straw,10% peat, 10% biogas residue, 25% vermiculite and 25% perlite (T3);a mixture of 40% corn straw, 5% peat, 5% biogas residue, 25% vermiculite and 25% perlite (T4);a mixture of 50% corn straw, 25% vermiculite and 25% perlite (T5);a mixture of 80% soil and 20% corn straw (T6);a mixture of 60% soil and 40% corn straw (T7);a mixture of 40% soil and 60% corn straw (T8);and a mixture of 20% soil and 80% corn straw (T9). The experiment was arranged in a randomized block design with three replications. The effects of corn stalk on seedling emergence rate, plant height, stem diameter, leaf area and seedling biomass were analyzed as well as the physicochemical properties of different substrates, including bulk density, total porosity, organic matter, pH value and EC values. Corn straw can be used as a suitable volume ratio instead of peat and biogas residue to raise seedlings, which can promote the growth and development of cucumber seedlings. To a certain extent, the substrate recipes of treatments T1 and T2 could improve the quality of cucumber seedling. The growth index data of treatment T1 at 40d of seed germination are as follows: plant height was (8.61±0.34) cm, stem diameter was (4.34±0.27) mm, chlorophyll relative content was (37.40±2.15) SPAD, leaf area was (60.21±1.69) cm2, root activity was (118.306±30.611) TTFμg/(g·h), and the content of organic matter of cucumber seedlings in T1 was significantly higher than that of CK1. There was no significant difference in the growth index between T2 and CK , but the biomass of root of (100.53±2.71) TTFμg/(g·h) at T2 was significantly higher than that of CK1. Therefore, corn straw had a certain role in promoting the growth of seedlings, which can be used instead of peat for the nursery substrate configuration, but it was necessary to control the volume percentage of corn stalks within 20% in order to avoid inhibiting the growth of cucumber seedlings.