Abstract: In this paper, a coil array eddy current sensor was developed using planar printed circuit board (PCB) plate, and the parameters of planar circular spiral coil were determined with a calculation formula. The distribution state of vortex field on the specimen crack was simulated and analyzed with a finite element software ANSOFT. A non ferromagnetic material aluminum plate was taken as the test pieces to carry out the crack detection and prove the validity of planar coil array sensor. The results show that the planar coil array eddy current sensor can detect tiny cracks on the aluminum plate, and with a good correlation between amplitude of output signals and geometric parameters of cracks.