The invention discloses a method for evaluating elasticity of oil well cement stone. The method comprises the following steps: (1) preparing and prefabricating cement paste for contrast, and pressing and curing to obtain cement stone; (2) drawing an axial stress-axial strain-radial strain-volume strain curve of the cement stone; (3) calculating Young modulus of the cement stone, thereby acquiring flexibility; (4) confirming an elastic strain limit of the axial strain through a knee point of the volumetric strain curve of the cement stone, drawing a vertical line to a horizontal axis from the elastic strain limit point, thereby forming a triangle by the vertical line, the axial strain curve and the horizontal axis, and calculating the area of the triangle, thereby acquiring elastic strain energy; (5) taking the flexibility as a horizontal coordinate and the elastic strain energy as a vertical coordinate, drawing a rectangular coordinate system, wherein a first quadrant is taken as a cement stone elasticity chart; and (6) dividing an elasticity comparison region on the elasticity chart at an elasticity coordinate point of certain cement stone and comparing elasticity magnitudes. According to the method provided by the invention, the elastic effects of common oil well cement and elasticity and toughness modified cement are directly and clearly evaluated; the test is simple; the cost is low; the popularization is easy.