A typical arid area in South Xinjiang was selected to study the temporal-spatial variances of soil salinity. Calibration sites were selected in the study area. Apparent electrical conductivities (ECa) were measured, and soil samples were collected in the calibration sites. The results showed there was a good correlation between soil salt content and the apparent electrical conductivity, so the interpretation model for soil salinity could be established. A mobile electromagnetic induction survey system was constructed to survey the study area with enough ECa data collected. The spatial variance could be studied with GIS and geo-statistics knowledge, and the temporalspatial variances could be rapid diagnosed by EM surveys over different times. The results showed serious salinization exited in the study area, and salinization in autumn was worse than that in spring, salinization in 2009 was more serious than that in 2008. 