A laboratory experiment was conducted to assess the effects of the freezing-thawing cycles(FTCs) on soil microbial biomass carbon(MBC),and CO_2 and CH_4 emissions from wetland soils in the continuous permafrost zone(TQ) and seasonally frozen region(JC) of Northeast China.Soil samples were incubated at different frost intensities [+5(control),-5,and-15 ℃] for 12 h respectively,and then thawed at +5 ℃ for 12 h.These freeze-thaw cycles were repeated for 0,1,5,10,and 15 times.The results showed that the CO_2 and CH_4 emission rates and MBC of two types of soil decreased after the first freeze-thaw incubation,and presented an increase and then decrease pattern and then trended to be stable with the increases of cycling times.Compared with the control(5 ℃) and low frost intensity(-5 ℃) treatments,high frost intensity(-15 ℃) significantly promoted CO_2 and CH_4 emissions but did not significantly influence MBC.At-15 ℃,the cumulative CO_2 emissions from TQ soil reached 679.99 mg·kg~(-1) after 15 FTCs,which was about 50% higher than that of JC soil(454.32 mg·kg~(-1)).The highest cumulative CH_4 emission from TQ soil was 334.49 mug·kg~(-1) at-5 ℃ after 15 FTCs,while this value was 600.07 mug·kg~(-1) at-15 ℃ for JC soil.The temperature sensitivities of methanogens might be different between these two frozen soils during the freezing-thawing cycles.Our results provide scientific data for the assessment of global climate change on soil carbon turnover in the main permafrost regions of Northeast China.