Resources dynamical allocation and management is always an important feature in cloud computing. Auto Scale allows users to scale their cloud resources capacity according to elastic loads timely, which has been widely used in mature public cloud. For private cloud, there are some different features from public cloud. It is more flexible to use Auto Scale technique to provide QoS guarantees and ensure system health. In this paper, we design a novel Auto Load-aware Scale scheme for private cloud environment. We describe scale in and scale out strategy based on prediction algorithm. We implement our scheme on OpenStack platform. Both simulation and experiments are carried out to evaluate our work. The experiments show that our scheme has better performance in resource utilization while providing high SLA levels.