Heat generation during cutting process affects the machined workpiece material and influences the cutting forces and tool wear. In this paper, a static thermal analysis model is developed to determine temperature rise in aluminum alloy (2A12) micro-cutting. The modified model is established based on two-dimensional steady state heat diffusion equation along with heat losses by convection film coefficients at the surfaces. A negative heat source is applied to simulate the heat loss during chip formation process. Effects of chip length and negative heat source on temperature distribution are discussed. The simulation results are compared with experiment data. The final results indicated that the model with negative heat source is more accurate than that without negative heat source and 20mm chip length give best temperature field fitting to the experiment.