| Chafers are important pests and economical insects , which play a significant role in agriculture and forest .The larvae of chafers named grub, which harm many kinds of plants and fruit trees .So, lots of researchers had studied them at home and abroad. The present systematics study of chafers still stays on the level of morphology, and the system of chafers is not identical. In this study the phylogeny of some chafers was based on partial nucleotide sequences (about 433bp) of the mitochondrial cytochrome b gene of 12 taxa .The sequences character were analyzed by bio-software package to construct molecular phylogenetic trees. This study will provide basic data for utilizing and preventing them deeply .The experiment progress included three steps, extraction of genome; amplyfication and sequence of Cyt b gene; analysis and discussion about data .1. Extracting and seguencing gene: The method of extraction was SDS-protein enzyme K digestion from samples kept in pure alcohol or storaged samples , then amplifying target DNA . The better results were purified and sequenced . (entrusting Sangon company to sequence )2. Editing sequence: the sequence was modified by ContigExpress, then edited by Editseq software . The total sequence 485 bp (including primer) of them were exported in fasta format.3. Aligning sequence : the target sequence were complete multiple alignment, and were exported in Clustal and phylip format.4. Constructing phylogentic tree: The sequence data were analyzed by Mega 2.1 and Phylip 3.6a software Package, nucleotide composition and genetic distance computed . Molecular phylogenetic tree constructed by Neighbor-Joining based on Kimura-2 Parameter model , parsimonymethods and Maximum likelihood method . From the analysis of results, conclusions were as follow:1. A and T base are rich in the obtained sequence of cyt b gene. Thedivergent sites concentrated on the third and second site , the ratio of transition and transversion became lower in company with the divergence time of them .The obtained sequence coded total 144 AA, in which 52.08% was variation.2. The phylogenetic relationships Sarabaeidae inferred from Cytb gene datashowed that the same genus assembled first one branch the clade of Protaetial (liocolaj Brevitarsis: (lewis,) and Protaetia (Potosiaj Famelica (Janson) was clearly separated from P.(poios\a)metallica Herbst.. M.holosericea (Fabricius,) and Mimelasplendens (Gyllenhal,) belonged to Popillia Silville genus .The amount of sequence divergence between these clade was significantly greater than whin the clade .3. Relationships of family: Phylogenetic tree showed that Trichiidae, Cetoniidae, Rutelidae, Dynastidae and Melolonthidae all belonged to pleurostict, they concentrated on one group in all molecular phylogentic trees. Scarabaeidae and Geotrupidae all belong to laparostict, which is far from the pleurostict.4. In this paper the phylogenetic trees inferring from single gene was not completely same. Cyt b gene was fit for distinction in intragenus and family. The relationship of molecular trees was almost parity the traditional Systematics. But, the more research about chafers was essential in future.
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