The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), caused by a newly discovered coronavirus, has been announced as a global pandemic by WHO on March 12, 2020. We aimed to provide a more accurate, object-oriented SEIR model for Epidemic as well as a thorough analysis for different intervention strategies and critical parameters. Based on the object-oriented mindset in computer science, we assigned properties to every independent patient, which includes age, likelihood of catching the virus, independent mortality rate, social activeness, awareness of the danger of the virus. We also considered macro level parameters including testing rate, positive rate. Based on the fatality data obtained, we estimated the occurrence time of the first case in China (excluding Hubei), Russia, Germany, and the United States using the model. Eight groups of virus-transmission simulation with different testing rate and quarantine ratio were conducted. The mortality data was found to be an effective and crucial parameter while the number cases can be decisive reflecting the severity of the pandemic.