In this paper, the effect and mechanism of microbially induced calcium carbonate (MICP) combined with carbon fiber for curing calcareous sand were investigated. The effect of carbon fiber on the effect of MICP on the consolidation of calcareous sand was investigated by a low-round grouting test, and the optimal amount and length of carbon fiber was determined. The test results show that the addition of carbon fiber can significantly improve the strength of microbial reinforced calcareous sand. In the low-round grouting test, the addition of carbon fiber can effectively improve the calcium carbonate production and specimen strength, and the calcium carbonate production in the fiber group increased by 15%~34% and the specimen strength increased by 135%~217% compared with the control group without fiber. In the case that the MICP cement could not be re-infused into the sand column, the strength of the fiber group increased by 11% compared with that of the no-fiber group.