The contamination of chloroplast and mitochondrial DNAs was a serious problem during genome sequencing of rice (Oryza sativa L.ssp.indica) by whole-genome shotgun strategy. Pulse field gel electrophoresis (PFGE) was utilized to purify rice genomic DNA, which could efficiently remove the organelles (chloroplast and mitochondrion) DNA and reduce the contamination ratio from 3% to 0.2%. At the same time, the rice DNAs yielded from yellow seedlings and green seedlings were compared, and the differences between HB method and NIB method in high molecular weight(HMW) DNA isolation were also studied. Finally, a set of methods for obtaining the whole and highly pure rice genomic DNAs were proposed, which included culturing rice yellow seedling; isolating, embedding and lysising rice nuclei, purifying and recovering rice genomic DNAs in low melting point (LMP) agarose gel by PFGE. Ultrasonic treatment on HMW DNAs in the melting LMP gel at 38℃ was reported at first time, it facilitated to obtain the desired DNA fragments for construction of shotgun library and gradient libraries.