Firstly, this paper introduces briefly white dwarfs, pulsating white dwarfs, the theory of star pulsation, asteroseismology on white dwarfs, white dwarf evolution program, and white dwarf pulsation program. Secondly, I do the asteroseismology work and compare to spectroscopy work for three DAV stars, namely G29-38, HS0507+0434B, and EC14012-1446. At last, I want to combine the asteroseismology work with the spectroscopy work for GD154 and hope to obtain a reliable result in the next work. According to the limb darkening effect produced by geometry position of different spherical harmonic degrees, Thompson made mode identifications for G29-38 in 2008. Mesh models are evolved by WDEC, adopting diffusion equilibrium profiles between C/He and He/H. The core compositions are 20\% carbon on the center of C/O core, 60\% carbon on the surface of C/O core, and linear profile between them. The asteroseismology results are consistent with the spectroscopy results of Xu et al. in 2014 but dis-consistent with other spectroscopy results. Fu et al. made new mode identifications on HS0507+0434B in 2013 according to their WET observations. Six triplets are identified with equally spaced frequency splitting values. Mesh white dwarfs are evolved by WDEC. The core compositions are from linear fittings to carbon profile of a white dwarf model from MESA. The asteroseismology results are close to the spectroscopy results of Fontaine et al. in 2003 and Koester et al. in 2009, but far from the spectroscopy results of Gianninas et al. in 2011. Combining the independent frequencies identified by Handler et al. in 2008 and by Provencal et al. in 2012, I make new mode identifications on EC14012-1446. According to the frequency splitting law and the equally spaced period spacing law, 6 $l$ = 1，4 $l$ = 2，5 $l$ = 3，and 10 $l$ = 1 or 2 modes are identified. The total stellar masses of white dwarfs evolved by MESA should be matched to the total stellar masses of white dwarfs required by WDEC. Taking the element diffusion into account, I do not adopt the diffusion equilibrium profiles directly when evolving white dwarfs in WDEC. The asteroseismology results are a little larger than the previous spectroscopy results. Reliable mode identifications and physical model evolutions are required for asteroseismology work on white dwarfs. Combining asteroseismology work and spectroscopy work is an effective and feasible method to study white dwarfs.
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