The basic principles of wavefront sensing based on phase diversity (PD) are introduced. And the phase diversity is extended from monochromatic or quasi- monochromatic light illumination to broadband spectrum light illumination. Based on lots of computer simulation and analysis, the validation experiment of broadband PD technology is designed. The integrating sphere is used as the light source, and the modulation transfer function (MTF) testing experiment of some optical system is established in the lab. The wavefront of optical system and the best position of focal plane are calculated by broadband PD technology, and the images collected are restored. Furthermore, the outfield imaging experiment is designed. The broadband PD is applied to solve the wavefront aberration according to the images collected. The result shows that the difference between wavefront aberration solved by broadband PD and the root mean square (RMS) of interferometric testing result is less than 0.03λ, and the difference of focal plane position solved by PD and MTF testing is less than 0.03 mm. The testing precision of broadband PD satisfies the requirement of engineering.