The invention discloses a safety evaluating method of pressure equipment containing crack defects, which comprises the following steps: 1, carrying out nondestructive testing and a standard stretching experiment; 2, obtaining a fully plastic solution factor h1 corresponding to the hardenability value n of different materials, and computing 1n(h1/h1(n=1)), wherein h1(n=1) is the value of h1 when nis equal to 1; 3, drawing a relationship curve between (h1/h1(n=1)) and n, fitting the relation curve into a linear relationship, recording the slope rate as B, and computing a defect size influence factor phi according to the formula phi=exp(-B), wherein exp presents an exponential function using a natural logarithm e as a base index; 4, establishing a failure evaluating curve and computing the positions of discontinuities; and 5, determining the plastic damage extent L'r and the fracture failure extent K'r of the pressure equipment, and judging the safety state of the pressure equipment containing the crack defects. In the method of the invention, the influence of the defect size factor phi to the safety is considered so that the evaluation is more accurate; phi is not limited by the material parameter n so that the invention can be simply and easily used for computing any materials.