Until now, there are only few researches about the effects of different population migration and quarantine strategies on the COVID-19 variations in China. Guangdong province has the largest gross domestic product (GDP) than the other provinces in China. Moreover, according to the present COVID-19 variations and control strategies, the Guangdong province adjusted the emergency response level of epidemic prevention and control from the first level response to the second level at Feb 24, 2020 (http://www.gd.gov.cn/). More and more workers will come back to Guangdong province from other provinces. Thereby, we choose Guangdong province as a case study to explore the effects of the population migration and quarantine strategies on the COVID-19 variations. Based on the present rigorous and extreme control measures in Hubei province, input population from Hubei province are not considered.