Abstract: The aim of this study was to analyze the immunological response to Mycoplasma pneumonia in Chinese Merino Sheep with different MBL genotype. MBL levels were measured in the four different individuals, 50 healthy Chinese Merino sheep with different genotypes were artifically infected with M. pneumonia under the same raising condition, while 20 sheep were the control group, the content of TNFα, IFNγ, C1, C3 in the serum were quantitatively assayed by ELISA on 1 day before infection (-1 d), and on 1 (the day of infection), 7, 14 and 21 day. The results showed that: 1)A and B type had low concentration of MBL, while C type’s MBL level was higher; 2) One week after infection, the percentage of IFNγ in the MBL A and MBL B was significantly lower than that of control group(P＜0.05), two weeks later, the level of C3 was lower and the TNFα was significantly higher(P＜0.05). Compared with the MBL A and MBL B at one week after infection, the level of IFNγ was significantly higher in the group of high concentration of MBL, two weeks later, the level of C3 increased and the level of TNFα was significantly lower (P＜0.05), the percentage of C1 had no significant difference among the groups (P＞0.05). Conclusion: there maybe some correlation between the lower concentration of MBL plasma and mycoplasma pneumonia, while there were some difference among the level of TNFα, IFNγ, C1, C3, the low MBL ones were likely to have more severe inflammatory response.