Abstract <p>The appearance, size, and density of micro ice crystal particles play a crucial role in weather forecasting and modification. Current observation methods are predominantly offline, requiring sample transfer from cloud chambers to microscopes for analysis, which lacks real-time capability and continuous monitoring. To address this, we designed and constructed an in-situ microscopic observation system for real-time monitoring of ice crystal formation and growth. This system successfully captured dynamic morphological changes and size distributions of ice crystals under both natural and catalyzed conditions. Using bismuth iodide (BiI₃) and silver iodide (AgI) as catalysts, it is observed that AgI significantly enhances ice nucleation efficiency, reducing the average ice crystal size to 30 μm and increasing the number density to 1 × 10⁷ ice crystals/m² at −16°C. BiI₃ showed a weaker catalytic effect. The system demonstrates high potential for applications in artificial precipitation, hail suppression, and climate research.</p>