In order to deeply understandnitrogen(N)transformation process of farmland black soil during non -growing season，with a laboratory simulation experiment，the effects of different freezing -thawing factors[freezing and thawing temperatures(freezingtemperature:-3，-6，-9，-12，-15 ℃；thawing temperature:2，5 ℃)，freezing -thawing cycles(FTCs)number(1，3，6，10，15；FTCs number 1 consisted of freezing at -3℃ for 6 days and subsequently thawing at 2℃for 1day.)，moistureregime(10%，20%，30%)]on the contents of inorganic N components and N transformation rate were investigated in the farmland black soil.The results showed that，the larger freezing -thawing temperaturerange(-15 ℃ /2～ 5℃)and the reasonable FTCs number(1～3)and moistureregime(20%～30%)werethe major driving factors affecting N transformation process of farmland black soil.The FTCs -treated soil ammonium N(NH4+-N)content，nitrateN(NO 3--N)content，net N mineralization rate and nitrifying rate all significantly increased with freezing temperature decreasing，and had no significant variations with thawing temperature increasing.With FTCs number increasing，the FTCs -treated soil NH4+-N content，NO 3--N content，net N mineralization rate and nitrifying rate all significantlydecreased.With moisture regimeincreasing，the FTCs -treated soil NH4+-N content significantly increased while the changes of NO^3--N content wascontrary，and net N mineralization rate and nitrifying rate both had no significant variations.Therefore，it is preliminarily concluded that FTCs could significantly promote N transformation of farmland black soil during non-growingseason，and was beneficial to the accumulation of soil available N.