The ultrasonical characteristics of inclined planar reflectors is investigated by the maximum amplitude method. The reflected ultrasound is varied by the reflector size, shape, inclination and using transducers. It was found that the detecting ability for planar reflectors was decreased with increasing transducer size and misorientation angle and increased with decreasing ultrasonic frequency, also the misorientation angle of planar reflectors affected significantly for the measurement of refklector size.