The chemical theories are used to describe process of coalbed methane(CBM) molecules' dissolution and bubbles formation.Moreover,forces and works of bubbles formation are analyzed,combined with real situation of the field production practice,bubbles formation influence of temperature,overlying pressure,reservoir water salinity,pressure drop and pore medium size are discussed.It shows that methane molecules' bubbles formation in the water includes methane molecules four process of bubbles dissolved in water,local gathered nucleation,bubbles formation and bubble burst,the air bubble growth and stability.The smaller overlying pressure is,the larger pressure drop is,the easier methane molecules form stable bubbles,during early period of CBM development,low temperature and low salinity are benefical to bubble formation when methane molecules move with the diffusion way.