Upon drying, the generated cracks on the soil surface can greatly weaken the mechanical properties of soils, thereby causing various geological engineering problems. Based on the bio-carbonation of reactive magnesia (RMC) method, this study investigated the feasibility of the spraying method in suppressing desiccation cracking and explored the effects of curing agent composition, urea concentration, RMC dosage and spraying sequence on the anti-cracking performance of soils. The results show that: (1) The formation of hydrated magnesium carbonates (HMCs), and the bio-carbonation product of RMC could enhance the cementation of soil particles and establish a bio-carbonation layer on the sample surface, which enables to effectively inhibit the desiccation cracking behavior of soils through decreasing the evaporation rate of moisture in the soil and increasing the tensile strength of samples; (2) The elevated urea concentration could significantly facilitate the bio-carbonation of RMC. In the case of 2.0 mol/L urea concentration, the maximum penetration resistance of the bio-carbonized sample increased by 195.5% after three wetting-drying cycles in comparison to that of the raw sample; (3) Both high RMC dosage and the post-spraying treatment of RMC solution impeded the infiltration of RMC within the soil matrix, which negatively affected the improvement of cementation performance for soil samples.