Abstarct: Problems caused by the accumulation of calcium carbonate and soil pH for the plants in arid and semiarid regions of the country due to the nature of soil parent material and little precipitation and increasing levels of saline and alkali soils cause production and applica-tion of more fertilizer is sulfur. However , the effects of sulfur in the soil on the biochemi-cal oxidation rate by microorganisms is dependent.The purpose of this study effect differ-ent factors soil include the amount of clay soil salinity and also spent time on the biochem-ical oxidation of sulfur was carried out in controlled conditions. This study in the labratouar the absence plant a factorial experiment baxsed on com-pletely randomized design with three replications in two experiments were performed. In the first experiment, treatments consisted of clay soil on three levels [low (less than 15 percent), moderate (15 to 30 percent) and high (greater than 30 percent)}, the amount of sulfur in two levels (0 and 400 kg/ha) with the presence or absence Thiobacillus inoc-ulums. In the second experiment the treatments included three levels of soil salinity {to low salinity (less than 4 ), moderate salinity (4 to 8 ) and high salinity (greater than 8 ) }, sulfur levels in two levels (0 , 400 kg/ha) with the presence or absence of Thiobacillus inoculum is a laboratory method was carried out couch. Results showed that after 90 days incubation, the soil samples of sulfur oxidation rate with increasing clay content and soil salinity, respectively, and significantly increased and decreased, The changes in the presence conditions of Thiobacillus inoculum more sever ocurred. Results showed that in the presence conditions of Thiobacillus inoculum sulfate soil sample to measure the amount of sulfate The third day in a clay soil with low, medium and high , respectively, 3.2, 3.8 and 3.9 times and in the absence of Thiobacillus inocu-lums , respectively, 2.5, 3.2 and 3.5 times increased. also the amount of sulfate in soil samples to measure the amount of sulfate Third day, salinity in the soil samples with low, medium and high, respectively, 3.64, 2.94 and 2.74 times and in the absence of Thiobacillus inoculum, respectively, 3.28 , 2.42 and 2.07 times increased. Most of the sulfur oxidation rater was conducted on the third day so that in the presence of Thiobacillus inoculum in the soil samples With low clay, medium and high , respectively , 50.3, 67.2 and 70.7 and in the absence of Thiobacillus inoculum , respec-tively, 33.6 , 50.3 and 53 micrograms per square centimeter per day of sulfur on was also in samples with low salinity, moderate and high in the presence of Thiobacillus inocu-lum, respectively, 62.7 , 66.6 and 56.6 and in the absence of Thiobacillus inoculum re-spectively 46.3, 39.5 and 37.9 micrograms per square centimeter per day of sulfur was achieved.