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Single-crystal superalloys have been commonly used in modern advanced aero engines to produce high-pressure high-temperature turbine blades. In order to extend the lifetime of single-crystal turbine blades, repair of cracked and worn ones is of great interest. Laser Solid Forming (LSF) is a prospective technology that can be used to repair single-crystal blades. In this study, the microstructure of the as-deposited and heat-treated LSF single-crystal superalloy has been characterized through optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The as-deposited LSF sample showed a directionally solidified columnar dendrites growing almost parallel to the building direction. Between the dendrites, nearly round microporosity and blocky MC carbide particles were dispersed uniformly. TEM results indicated that many nano γ′ particles precipitated in γ matrix. In addition, during LSF deposition process, Stress was formed, which generated plenty of dislocations. During heat treatment, the LSF sample experienced fully recrystallization. The recrystallization grains were in different size, and twins were found in some recrystallized grains. Because the residual stress was fully released during heat treatment, the size and shape of γ′ precipitates in the recrystallized and un-recrystallized regions were similar to those in conventionally cast samples.