Abstract: Microbes are known to show a great spatiotemporal distribution, and exert extensive and intensive geological agents in both modern days and Earth history. These features make the microbes play important roles on great changes of Earth environments, enabling important and wide applications in geoengineering including the pollutant remediation, decrease of atmospheric CO2, geohazards prevent, as well as toxic decrease. This necessitates the cross-disciplinary construction from microbial Earth to microbial geoengineering. It is well known that microbes, the engineer of elemental geochemical cycles, have played the key roles in the geoengineering fields including carbon sink, ecological remediation and the agriculture practice. The carbon pump and the microbial carbon pump, the important mechanisms to transport the atmospheric CO2 into the sediments or seawater, are documented to mainly regulate by the microbial communities either in the sea or on the land. Microbes are widely involved into, and known as the engineer of the geochemical cycles of greenhouse gases including CH4, CO2 and N2O. These microbial processes could be exploited in the geoengineering to promote the carbon sink or decrease the carbon release. Microbial transformation of a series of metal ions as well as the degradation on organics has been widely used in the ecological remediation of polluted environments. Microbial release of elements including carbon, nitrogen, phosphor etc., from a variety of minerals is applied in agriculture practice. The artificial microbial mixtures on the basis of natural communities could be used as the nature-based fertilizers in the farming practice.Microbial roles, played on the precipitation and erosion of minerals, could also be applied into rocks and soils engineering, deep Earth engineering and mining industry. The microbial application to these geoengineering will greatly save the costs, remarkably promote efficiency and noticeably protect the natural environments. Microbial transformation of the expansive clay minerals into noexpansive ones which could be applied into the oil recovery by water flooding as well as the rocks and soils geotechnical engineering. Carbonate factory is known to be primarily induced by microbial communities via the precipitation of calcium carbonate from the fluids which could be introduced into the building of artificial islands in the sea, the filling and repairing of rock cracks, cementation of coarse grains in a variety of geoengineering. Microbial erosion of minerals could be exploited into the mining industry via the release of metals of economic significance from ores. The presence of the so-called deep biosphere, featured by the dominance of extreme environment microbes, will exert positive and negative effects on the underground storage of dangerous materials including the nuclear wastes, CO2 and hydrogen gas. The investigations on the microbial roles on these materials as well as the storage containers are of in particular importance.Whilst most microbial geoengineering has been conducted to prevent and control the geohazards that have come into being in natural environments, microbes could further provide the early warning of some geohazards including the biotic or ecological crisis, climatic and environmental disasters, as well as landslides due to their sensitive response to minor environmental changes. To construct the early warning geoengineering via the on-site filed observatory network is of important so that we could take some measures to prevent the occurrence of the geohazards, or make the positive use of the microbial roles but suppress the negative roles.