Abstract: The occurrence of keel bone fractures（KBF） is generally higher in laying hens housed in cage or none-cage systems. KBF causes physical and psychological damage, reduces welfare levels and affect the behavioral response of laying hens. To investigate whether KBF could affect the social competition, the responses of competitive behavior were compared between fractured and unfractured laying hens at their late laying. In this experiment, palpation and X-ray were used to determine the keel bone condition of Lindian hens housed individually in traditional cages at 65 weeks of age. Laying hens were divided into normal keel bone group（NK） and keel bone fracture group（FK）. After paired combat test, three keel fractured laying hens and three unfractured laying hens were regrouped in each enriched experimental cage, to research the social competitive rank index（CBI） of fractured and normal hens. Then, a food competition test was performed. Finally, keel bone tissues and serum samples were collected from chickens with normal or fractured keel bone to detect the expression of inflammatory factors. The results of the paired combat test showed that keel fractured laying hens scored significantly lower than normal laying hens（P＜0.05）. In addition, the CBI of fractured Lindian hens was significantly lower than that of the normal hens（P＜0.05） under the social competition test of the recombinant flock of laying hens. However, there was no significant difference in feeding time between keel fractured and normal Lindian hens in the feeding competition test（P＞0.05）. The mRNA expression levels and serum concentration of inflammatory factors from fractured laying hens were higher than that of the normal hens（P＜0.05）. Therefore, the KBF reduced the fighting ability of laying hens and made them with a lower social competition. The chronic inflammation state caused by the keel bone fracture might be the one of reasons of the decreased social competitiveness behavior for fractured laying hens.