Molybdenum (Mo) is an essential element of plants.Rational Mo fertilizer application to soil requires information of the Mo concentrations in soil.Determination of soil available Mo has great significance in evaluating the soil Mo supply.Mo concentration in extract is often determined with graphite furnace atomic absorption spectrometry or polarography methods,which are not easily operated and consume time.In this paper,oxalic acidoxalate ammonium solution (pH 3.3,Tamm reagent) was used as extraction solution to extract available Mo form in soil.The Mo in the extract of Tamm solution was determined directly by the inductively coupled plasma mass spectrometry (ICPMS) with collision model using high pure helium (He) gas.103Rh was used as an internal standard element to correct the matrix effect.The results showed that the detection limit of the proposed method was 1.02 μg/L.The measured soil available Mo values were consistent with the standard values of two national soil standard materials (GBW).The recovery rate was in ranges of 95.1%~152% when adding the standard Mo solution to the soil.The relative standard deviation of determinations for 5 soil samples with 6 repeats per sample was less than 8%.It is suggested that ICPMS with He gas collision mode could be used for determining soil available Mo extracted by Tamm reagent.The proposed method saves time and is suitable for the batch measurement of soil samples.