Bivalve live in aquatic environment and the water temperature can affect their immunity directly. In this research, the scallop Chlamys farreri was injected with 10 4 or 10 7 CFU mL −1 Vibrio anguillarum and cultured at 11°C, 17°C, 23°C, and 28°C, respectively. For the control scallop, only phosphate-buffered saline (PBS) was injected. Then total haemocytes and granulocytes were measured by ELISA using monoclonal antibodies. In the meantime, expressions of six immunity-related genes, including lipopolysaccharide and β-1, 3-glucan binding protein ( CfLGBP), C-type lectin ( CfLec-2), Toll-like receptor ( CfTLR), Lysozyme ( CfLYZ), superoxide dismutase ( SOD), and phenoloxidase ( CfPO) in haemocytes were measured using quantitative real-time PCR. The results showed that total haemocytes counts in 10 4 CFU mL −1 injection groups showed no differences compared to the control group at all temperatures. However, they varied significantly in 10 7 CFU mL −1 injection groups at 3 h at 11°C, 6–12 h at 17°C, 3–48 h at 23°C, and 12–48 h at 28°C. Granulocytes counts in 10 4 CFU mL −1 injection groups showed no variance compared to the control group at all temperatures, except for 12 h at 23°C, and 24–36 h at 28°C. They were significantly decreased in 10 7 CFU mL −1 injection groups during 6–48 h at 11°C, 12–48 h at 17°C, 3–48 h at 23°C, and 3–72 h at 28°C. The expression levels of six immunity-related genes in haemocytes of 10 7 CFU mL −1 injection groups were significantly higher than those of control group and 10 4 CFU mL −1 injection groups at all temperatures. The results indicated that infected with high concentration of vibrios, haemocyte counts, granulocyte counts and the expressions of immunity-related genes in scallop C. farreri were significantly affected by environmental temperature.