In order to get the high quality genome DNA from Spirulina,the two extraction methods,i.e.the ultrasonic method and lysozyme method were studied.The results show that the degree of breaking the cell wall is an important factor to restrict the quality and output of the genome DNA.The ultrasonic method and lysozyme method were able to gain the high quality and output of genome DNA from Spirulina,but the ultrasonic method could not be controlled easily while the lysozyme method could extract the genome DNA more easily.