Microbially induced calcium carbonate precipitation (MICP) technique is one of the promising methods that can improve the mechanical behaviors of the sand materials via the precipitated calcium carbonate crystals. However, the uniformity of bio-cemented sand materials is a serious problem and hinders the engineering applications of MICP technique. This study carries out the effects of different calcium sources (calcium chloride and calcium acetate) on the uniformity of bio-cemented sand columns (3cm in diameter and 11cm in height, 5cm in diameter and 100cm in height) treated by one batch of MICP injection and the MICP process. The calcium carbonate content and unconfined compressive strength results of bio-cemented sand samples demonstrate that the calcium acetate can enhance the length of the cementation path, improve the calcium carbonate distribution along the grouting direction, and reduce the strength differences among the bio-cemented sand materials. Combining with the results of ammonium ion concentration and calcium ion concentration in the solution environment, when the calcium acetate acts as the calcium source, the rate of MICP reaction is slower than that of MICP reaction promoted by calcium chloride, benefitting the transmission path of the undecomposed urea and the free calcium ions, thereby improving the uniformity of bio-cemented sand materials.