The cohesion and internal friction angle under the different EN—1 contents, curing ages, compaction degrees and water contents treated with EN—1 were determined by using direct shear test. The results showed that the shear strength of Pisha sandstone solidified soil had varying degrees of increase than plain soil with the increase of EN—1 contents and curing ages under the EN—1 contents, curing ages, compaction degrees and water contents in this experiment after EN—1 were added. The shear strength of Pisha sandstone solidified soil was the biggest when EN—1 content was 0.20% and curing age was 30d. The shear strength of Pisha sandstone solidified soil increased with the increase of compaction degree and the decrease of water content after EN—1 was added. Consequently, in order to make the EN—1 solidified soil have favorable shear strength and satisfy engineering demand, it suggested that EN—1 content was 0.20%, curing age was 7~15d, compaction degree was greater than 95%, and water content was slightly less than optimum moisture content when EN—1 was used practically to solid and protect slope in Pisha sandstone region.