Abstract: In response to the apparent defects and performance deterioration of concrete caused by early water migration and evaporation behavior, this paper systematically investigates the optimization effect and influence law of xanthan gum-based water-retaining agents on the performance of C40 concrete under sealed, exposed, and 6 m/s wind-speed curing conditions. The results show that with the increase of the dosage of the water-retaining agent, the slump of the concrete first increases and then decreases, the pressure bleeding rate gradually decreases, the emptying time of the inverted slump cone gradually prolongs, the compressive strength first increases and then decreases, the shrinkage rate gradually decreases, and the apparent quality first improves and then deteriorates. Specifically, when the dosage of the water-retaining agent is 0.02%, the adverse effects on the concrete slump and the emptying time of the inverted slump cone are relatively small, which can significantly reduce the pressure bleeding rate of the concrete. When the dosage of the water-retaining agent is 0.03%, it can obviously eliminate the differences in the effects of different curing conditions (such as sealed, exposed, and 6 m/s wind-speed) on the mechanical properties of the concrete, and enhance the 7 d and 28 d compressive strength of the concrete. Moreover, under this dosage condition, the water-retaining agent can minimize the pore area ratio and the number of cracks on the concrete surface, eliminate surface color differences, and improve the apparent quality of the concrete