The effects of EC (electrical conductivity of soil saturation paste) and Mg2+ alkalinity on soil microbial biomass and basal soil respiration in alkalized magnesic soils were investigated. The study was conducted along the border area of the alluvial fan of Chang Ma of Shu Le He River. Ten sites were chosen and thirty soil samples were taken. The results showed that microbial biomass C(N) and basal soil respiration negatively correlated with EC, exchangeable Mg2+ percentage and Mg2+/Ca2+, while the metabolic quotient (qCO2) positively correlated with EC, exchangeable Mg2+ percentage and Mg2+/Ca2+, which indicated the adverse effect that salinity and Mg2+ alkalinity stressec on soil microbial community.