Abstract: Objective　Through dynamic detection on COVID-19?specific IgM and IgG levels to understand the changes of specific antibodies in critical and non-critical patients with COVID-19. Methods　Sera of 30 COVID-19 patients, among whom 20 critical and 10 non-critical, confirmed in Tianjin, China from January 2020 to March 2020 were collected consecutively, tested for SARS-COV-2 specific IgM and IgG antibodies and analyzed vertically. Results　1. The positive rates of specific IgM and IgG in 0-6 days after symptom onset were 42.86% and 28.57%, respectively. As the disease progressed, the positive rate of both antibodies gradually increased. The positive rate of both antibodies began to decrease around 5 weeks later after symptom onset. Within 28 days after the symptom onset, the IgM and IgG level of both critical and non-critical patients were increasing and started to decrease . Especially for the critical patients, the IgM and IgG decreased obviously. 2. The IgG of critical patients were higher than that of non-critical patients and the difference was statistically significant in 28-33 days after the symptom onset(P＜0.05). 3. In 28-33 days and 34-40 days later after the symptom onset, the difference between the two antibodies within critical patients was statistically significant(P＜0.05). 4. In the recovery phase, the IgG level of critical patients was higher than non-critical patients, with statistical significance(P＜0.05); during their own recovery phase, within critical patients themselves, the IgG was higher than IgM, with statistical significance(P＜0.05). Conclusion　The specific IgM and IgG antibodies level of COVID-19 patients takes on the trend of increasing first and decreasing later as the disease progresses. Compared with non-critical patients, the specific IgG in critical patients is higher. Continuous high level of IgG might be the warning index of critical situation.