  This paper introduces Bohmian mechanics (BM) into the intense laser-atom
physics to study high-order harmonic generation. In BM, the trajectories of
atomic electrons in intense laser field can be obtained with the Bohm-Newton
equation. The power spectrum with the trajectory of an atomic electron is
calculated, which is found to be irregular. Next, the power spectrum associated
with an atom ensemble from BM is considered, where the power spectrum becomes
regular and consistent with that from quantum mechanics. Finally, the reason of
the generation of the irregular spectrum is discussed.
