Reclamation of marshland to farmland has great effects on global carbon cycling and inducing feedbacks to global climate change. Soil microbial properties are the most sensitive and indicative factors of land use changes that can reflect the dynamics of soil organic carbon (SOC) in the early stage. This study took the typical marsh wetland, wetland reclamation to paddy field (15 a) and soybean field (25 a) as the objectives to research the effects of reclamation on the soil microbial properties in the Sanjiang Plain, Northeast China. The results showed that the contents of SOC and total nitrogen (TN) were significantly decreased after marshland reclamation (P<0.001). The average SOC content was reduced by 31.50%, 51.38% and 49.81%, 63.88% of TN, respectively. The reduction of soybean field was higher than that of paddy field and the high TN reduction relative to SOC induced the decrease of soil quality. The soil microbial biomass carbon (MBC) and basal soil respiration (BR) were also significantly decreased (P<0.001), the availability of SOC and nutrients decreased and caused the decline of the microbial activity. Meanwhile, the differences of MBC and BR between 0~10 cm and 10~20 cm soil layers weakened and the heterogeneity decreased after reclamation. The microbial quotient showed a decreasing trend and the difference in 0~10 cm soil layer of soybean field and wetland was not significant (P=0.728), while that of 10~20 cm was significantly different (P=0.005), reflecting the decrease of soil labile organic allocation after reclamation. The soil metabolic quotient (qCO_2) of paddy field increased and that of soybean field significantly decreased (P=0.003) indicating the varied microbial carbon use efficiency of different land use types. The qCO_2 had significantly positive correlations with SOC and TN by regression analysis, suggesting that the substrate use efficiency of soil microbes decreased with the improvement of soil nutrients condition. This study manifests that the soil biogeochemical cycling will be greatly influenced by the changed microbial properties.