This For mastering the effect of particle size to strength and deformation characteristics of sand under high pressure, DRS-1 high pressure direct shear test system is used in shear test for 3 groups of sand under pressure of 12 to 15 MPa. Through analysis of the test results, it is obtained that standard sand under high pressure shows strain hardening and volume contraction characteristics. The relationship curves of stress-strain and volume contraction-shear strain appear as hyperbola, they can be simulated by Duncan-Chang hyperbolic model. Sand with small particle size has better group, greater density and higher strength, but the shear contraction is not obvious. Sand with poor group has particle crushing under high pressure, which makes the soil particles rearrange and then the average porosity decreases at the same time large pores disappear, so finally it shows a more significant shear contraction characteristic.