Abstract: This experiment was conducted to study the safety evaluation and minimum immune-doses of the recombinant fowl pox virus expressing S1 gene of infectious bronchitis virus and IFN-γ gene. The vaccines were chosen and diluted with the saline water. 7-day-old SPF chickens were inoculated in the endothelium under the wing at the dose of 1.0 ×10⁵PFU per chicken, local reaction appeared three days later, local swell became the largest at the 5th day. The inoculated chicken showed no sign of other discomforts,and inspirit, appetite and development were the same as controls. The results indicated that the vaccine was safe for chicken. The vaccine was diluted to 1.0 ×10¹~1.0×10⁴ PFU, and the 28-day-old SPF chickens were inoculated as above, then challenged with infectious bronchitis virus LX4 strain 3 weeks after inoculation. The results showed that the chickens inoculated in the dose range of 1.0×10² to 1.0×10⁴ PFU could induce local reaction, morbidity and mortality was reduced, and the protection rate was exceed 73%, but the inoculum of 1.0×10¹ PFU can induce local reaction partially (5/ 11), and the protection rate was 64%. These results indicated that there was a correlation between the local reaction and the efficiency, and the local reaction can reflect the efficiency of the vaccine. According to the fact of vaccine production and use, the optimum dose of the vaccine was 10³PFU.