Purpose: Modifying soil surface conditions is essential in managing water and soil resources. Although the use of soil microorganisms in the bioengineering management in soil and water conservation has been confirmed, the controllability of the surface cracks morphometry on petroleum-contaminated soils using microorganisms has yet to be studied. Therefore, this study aimed to investigate the effect of inoculating soil microorganisms on changing the surface cracks' pattern of soil contaminated with petroleum.Materials and methods: In 2022, the studied soil was taken from Iran's Tehran Oil Refinery area from the top 30 cm of the earth's surface and transferred to the Rain and Erosion Simulation Laboratory of Tarbiat Modares University at the Faculty of Natural Resources. The predominant cyanobacteria of Microcoleus sp. Oscillatoria sp. Lyngbya sp. Nostoc sp, and Phormidium sp. bacteria of Bacillus sp. and Azetobacter sp. fungus of Penicillium oxalicum were identified, purified and proliferated. The study was conducted at a 0.5 x 0.5-m plot scale in two replications for four treatments. Uncontaminated and gasoil-contaminated soils, during one month, were inoculated by bacteria, cyanobacteria, and fungus. The soil was contaminated using 720 mL of gasoil evenly sprayed. The morphometric characteristics of soil surface cracks were investigated using the PCAS software.Results and discussion: Results indicated that soil microorganisms influence the soil cracking patterns. So, the mean area, length, and width of cracks increased by 99.55%, 50.90%, and 29.60% in uncontaminated plots inoculated with cyanobacteria compared to the control treatment. In gasoil treatment, fungus-inoculated soils performed better than control plots, and the mean area and length increased by 19.51% and 29.58%, respectively, while width decreased by 17.29%. Microorganisms caused the agglutination of aggregates by secreting enzymes and exopolysaccharides, stabilizing soil particles, generating cracks, covering the soil surface, and improving the soil's rheological properties.Conclusion: Finally, the results of the present study showed that modifying the surface of the petroleum-contaminated soil by inoculating soil microorganisms is a way to improve the hydrologic and rheologic characteristics of the soil.