In order to understand the nitrogen transformation process of non-growing season farmland black soil,the effects of different freezing and thawing factors on the content of soluble nitrogen components in farmland black soil were studied by indoor freezing and thawing simulated culture experiment.The results showed that the main driving factors affecting the content of soluble nitrogen in farmland black soil were large temperature difference of freezing and thawing,appropriate number of freezing and thawing cycles （1-3） and water content （20%-30%）.With the decrease of freezing temperature,the contents of soluble inorganic nitrogen （DIN,NH₄⁺-N+NO₃^--N） and soluble total nitrogen （DTN） in freezing-thawing soil increased significantly,and the highest values were 89.84,101.99 mg/kg,respectively,at-15℃.The content of soluble organic nitrogen （DON） was synergistically affected by melting temperature.With the increase of thawing temperature,the contents of DIN,DON and DTN in freezing-thawing soil did not change significantly.DIN content in freezing-thawing soil decreased significantly with the number of freezing-thawing cycles increasing,and reached the minimum （83.21 mg/kg） when the number of freezing-thawing cycles in-creased 15,while DON and DTN contents increased first and then decreased,and reached the maximum value when the number of freezing-thawing cycles increased 6 and 3,respectively.With the increase of water content,the contents of DON and DTN in freezing-thawing soil increased significantly,and the highest values were 20.57 and 107.62 mg/kg,respectively,when the water content was 30%,while DIN content had no significant change.In conclusion,freezing-thawing significantly promoted nitrogen conversion in non-growing season farmland black soil,and was beneficial to soil available nitrogen accumulation.