This paper makes defect location maps for cylinder component ultrasonic testing by using Contour Method and finds that the generation of error of Contour Method for porosity defects reconstruction in cylindrical member is affected by the positioning angle. The experimental results are verified with flaw echo signal which is simulated by finite element software of PZFlex. The influence of the defect location, size and signal attenuation for the positioning angle is analyzed, which lays a foundation for further defect boundary reconstruction.