The annual average temperature in north of northeastern China is lower and the low-temperature weather lasts for a long time, which makes it difficult for the returned maize straw to decompose in the season. Decomposition Process and effect of different buried depth of maize straw were explored to provide theoretical foundation and scientific basis for suitable way selection of maize straw returned in north of northeast China. The study based on location test of different maize straw returning approaches, maize straw buried in the 0, 15, 30 cm depth were set in traditional ridge pattern using the method of nylon mesh bags. The decomposing process of maize straw in different buried depth and changing rules of content of soil carbon, nitrogen and activities of related enzyme were studied during the maize straw decomposing. The results showed that the decomposition rate of maize straw of 10-20 cm, 20-30cm and 0-10 cm buried depth were 81.89%, 75.64% and 60.67%, respectively in the current season, and the decomposition rate of maize straw of different straw returned pattern were 84.92%, 77.54% and 65.26%, respectively in the current season; conditions of soil water and heat of 10-20 cm buried depth was the best in the growth period,and content of soil carbon and nitrogen content were both higher, activities of soil enzyme was also stronger, which was benefit for accelerating the effective decomposition of returning straw.