With the improvement of the algorithms and hardware, phase diversity wavefront sensing technology becomes an important developing direction of the wavefront sensing technology, which is attributed to many advantages such as simple configuration, common path detection and so on. Phase diversity wavefront sensor is simulated not only for point sources but also for extended sources. An experimental testbed is built based on point source to detect the static Zernike aberration. Numerical simulations and experimental results demonstrate that phase diversity wavefront sensing technology can retrieve the wavefront accurately. Under the given experimental condition, the root mean square of the residual aberration is about λ/100 for the low order aberrations and less than λ/50 for the random aberrations.