[Objective] The aim of this study is to isolate Chlorella vulgaris (chlorella) and extract its genomic DNA. [Method] Both the dilution method and drip method were employed to isolate chlorella from lake water samples; the conditions for culturing chlorella were optimized and its genomic DNA was extracted by improved CTAB method and SDS method. [Result] The proper conditions for chlorella culture were as following: temperature 20-25 ℃, illumination 4.39-5.86 W/m2 and rotational speed 100-150r/min; improved CTAB method was suitable for extracting genomic DNA from chlorella. [Conclusion] The study is helpful to study the chlorella at molecular level and promote the exploitation and utilization of chlorella resources.