Biodegradable magnesium alloys is promising materials for medicine application. The corrosion rate and type of corrosion are ones of most important properties for this kind of materials. Fine-grained biodegradable alloys AZ31 (hot-rolled) and ZK60 (extruded) were studied in present work with using in-situ methods such as hydrogen evolve corrosion rate evaluating and incessant surface observation and ex-situ methods such as weight loss and confocal laser scanning microscopy investigation. Experiment methodic include immersion test in SBF (0.9% NaCl aqueous solution) in 120 hours with 37 oC with recirculating corrosion media. Hydrogen evolve was measuring with burette with frequency 1 hour, surface observation made by high-definition camera, pH was measuring twice a day. Corrosion rate curves, 3D corrosion surface morphology and videos shown staging of corrosion damage were received. As a result, ZK60 is less corrosion resistant and addicted to pitting corrosion, whereas AZ31 shown filiform corrosion.