Based on the experimental results of micro-bubble controlled growth in MEMS(micro-electro-mechanical system) devices，the bubble growth process could be divided into four stages，namely，nucleating，spherical bubble，bubble restrained by lateral wall，bubble elongating along the channel.A physical model of micro-bubble growth in the rectangular microchannel was established by considering the micro layer of liquid in the heater.Numerical simulation of micro-bubble growth in the micro restrained space was performed by the Level Set Method and the characteristics of micro-bubble growth were obtained and analyzed.The simulated data showed that micro-bubble grew rapidly in the early stage but grew slowly in the late stage due to the increasing condensation rate on the interface.The results also indicated that the initial temperature of liquid，width of the microchannel，width of the microheater，and the heating voltage had remarkable effects on the bubble inception and bubble growth rate.