Abstract: Microbially induced calcium carbonate precipitation technology(MICP) is widely used in the field of civil engineering. In order to better understand the effect of microbial reinforcement on the calcareous sand site, a low pH one-phase grouting method was adopted to carry out laboratory analysis tests and field loading tests on the reinforced calcrete sand site. The unconfined compression test, shear wave velocity test, and scanning electron microscope test were carried out through drilling sampling. The test results show that under the same reinforcement conditions, the different forms of calcium carbonate precipitation will lead to a large difference in strength. In the field loading test, the plate load test was carried out after the reinforcement and maintenance of the microbial site, and the site was kept dry. According to the plate load test, it was found that when the load gradually increased, the soil around the bearing plate began to crack and extend, and the soil mass experienced large displacement settlement and crack expansion during the final failure. It is also proved that the method of on-site expansion of carrying strains is desirable in microorganism reinforcement of islands and reefs.