A sensor array for multi-crack detection, consisting of complementary open-ended waveguide resonator rings in a microstrip configuration, has been designed to address, the challenges of simultaneous detection and low detection accuracy in the multi-form crack distribution of large metal structures, such as aircraft wings. The sensor array comprises complementary open-ended waveguide resonator rings of different sizes, which can detect characteristic parameters of straight cracks, pinholes, and star-shaped cracks. Experimental results demonstrate that the maximum detection sensitivity of the sensor array to parameter variations in the three types of cracks reached 150 MHz/mm, and the smallest detectable size of a straight crack is 10 mm×1 mm×0.1 mm. This sensor combines the advantages of strong radiation capability of complementary openended resonator rings, ease of surface conformability and substrate-integrated waveguide with low loss, high quality factor, and small size. It enables simultaneous detection of multi-form cracks on metallic materials, and offers advantages such as high sensitivity and wide detection range.