design: 1.The DNA molecules to be sequenced were broken into 200-500 bp fragments by ultrasonic wave; 2. The ends of the broken genome were flattened; 3. The 3 'ends of the flattened fragments were added with a and 5' ends for phosphorylation; 4. The repaired fragments were spliced; 5. The spliced DNA fragments were amplified by PCR;  6. The amplified library was purified by magnetic beads.