Density of dislocations in the near-surface layer was investigated in X-cut LiNbO3 depending on thermal annealing in the temperature range of 400°C–600°C. A dynamic model of randomly distributed dislocations has been developed for LiNbO3 by using X-ray diffraction. The experimental results showed that the dislocation density of the near-surface layer reached the minimum at the thermal annealing temperature of 500°C, with the analysis being performed when wet selective etching and X-ray diffraction methods were used. We concluded that homogenization annealing is an effective technique to improve the quality of photonic circuits based on LiNbO3. The results obtained are important for optical waveguides, LiNbO3-on-insulator-based micro-photonic devices, electro-optical modulators, sensors, etc.