With the development of cloud computing, cloud computing cluster will need to be upgraded or replacing outdated hardware. Therefore, the cluster will evolve from the initial homogenous environment into heterogeneous environments. Hadoop is originally designed to be applied to homogeneous clusters, when the cluster goes heterogeneous, the performance of Hadoop will face a downward trend. This paper addresses the problem of how to improve the performance of Hadoop in heterogeneous environments. We study the evaluation methods of server performance and Hadoop technology. Then we present a method of evaluating node performance in cloud computing environment. Base on this method, we propose an algorithm for dynamic storage allocation that based on node performance evaluation. Experiments show that this algorithm can improve the ratio of data-local map tasks and shorten job runtime in heterogeneous Cloud Computing environment.