Abstract: The diffusion process of liquid vapor in a gas bubble has been investigated numerically. With the assumptions of (1) spherical gas bubble; (2) constant temperature at gas-liquid interface; (3) no circulation inside the bubble, the mass transfer equation is developed as: Initial conditions C(r, 0)=C0 Boundary conditions C(R, t)=Cf It is also assumed that the pressure within the bubble is in equilibrium with ambient pressure during the bubble growth A stepwise approach has been proposed to solve the moving boundary problem. The results show that Dt/R02 and Ps/P are the main factors for the dynamics of bubble growth. Generally speaking, increasing liquid temperature Tc and diffusitivity D, or reducing the ambient pressure P and initial bubble radius R0 favor the mass transfer, especially as PS/P→1, the enhancement of mass transfer is more obvious.