SMS (Short Message Service) gateway has characteristics such as high concurrent capacity, high peaks, difficult to predict and high resources consumption. How to improve the system efficiency and stability has always been one of the key issues for the telecom operators to solve. This paper presents elastic SMS cloud gateway design and an elastic control algorithm, which can realize load sensing by dynamic resource control through the cloud computing platform, and improves SMS gateway service quality and the efficiency of resource utilization. Results of test on simulation environment show that, comparing with existing algorithms, the proposed algorithm is more efficient on scaling control, and has less resource utilization jitter on the condition of cluster size change.