The numerical model of temperature filed for micro-droplet deposition manufacture was established by adopting finite element method and element birth and death technology. The transient evolution of temperature filed was simulated during fabricating 7075 aluminium alloy thin-wall part by micro-droplets. The results show that the forming temperature filed of thin-wall part presents circumferentially dynamic change along with the moving of droplet depositing position; the thermal cyclic curves of different droplet element nodes include different number of temperature peak and valley values. With increasing the height of deposited layer, the cooling rate of adjacent overlapping droplets from the first to the tenth layers was decreased gradually, the high temperature region in deposited layer was enlarged gradually and the variable temperature gradient was shown in part building orientation, which causes the grain size of adjacent overlapping droplets to change. Experiments were carried out to validate the proposed numerical model in this paper. The simulated result and the experimental results are in good accordance.