Abstract: The inspection proficiency of nondestructive testing laboratory can affect directly the reliability and consistence of inspection results. In the paper, two statistical methods of Z score and En ratio are used for the proficiency comparison in nondestructive testing laboratory to verify their inspection ability. According to the characteristics of nondestructive testing laboratory and based on welding ultrasonic testing, the simulated comparison tests are designed. Using the two statistical methods, the comparison results are analyzed, and the inspection ability of every simulated laboratory is evaluated. The comparison results show that the evaluation conclusions obtained from Z score and En ratio methods are similar, and both of the two statistical methods can be used for testing the proficiency of non-destructive testing laboratory.