In order to explore the effect of straw biochar on vertical migration of inorganic nitrogen and phosphorus in surface layer of black soil during freezing-thawing period.This research adopts the indoor simulation of freezing-thawing cycle experiment, set the freezing-thawing and not-freezing-thawing, freezing-thawing cycles, biochar apply three influence factors, to analyze the vertical migration characteristics of soil surface inorganic nitrogen and phosphorus under freezing-thawing with different straw biochar apply. (1) Results show black soil surface freezing-thawing and not-freezing-thawing, freezing-thawing cycles and biochar apply have significant effect on NO₃^--N, NH₄⁺-N and PO₄^3--P inorganic nitrogen and phosphorus migration liquid total volume, total concentration and total amount of migration through freezing-thawing and not-freezing-thawing, freezing-thawing cycles and biochar apply.(2) The leaching time was shortened with the increase of freeze-thaw action and prolonged with the increase of biochar application.All treatments of inorganic nitrogen and phosphorus migration liquid volume show a decrease trend with the increase of biochar input. The total volume of migration liquid in not-freezing-thawing group show a slowly decrease trend as the incubation period increase. The total volume of the migration liquid volume in the freezing-thawing group increases sharply in the 5th freezing-thawing cycle test, and then became stable. (3) The effect of biochar on the vertical migration and accumulation of inorganic nitrogen and phosphorus under freeze-thaw action was analyzed. During the same control period, the inhibition of biochar on the vertical migration of inorganic nitrogen and phosphorus in the freeze-thaw group was greater than that in the non-freeze-thaw group.Because of changes in the physical properties of the soil,the accumulated migration of the freezing-thawing group NO₃^--N,NH₄⁺-N and PO₄^3--P changed dramatically around the fifth freezing-thawing cycle.To sum up, biochar can effectively retain nutrients during freezing-thawing period, and the research results can provide some theoretical support for the prevention and control of rural surface pollution during thawing period in cold regions.