The performance of processor has improved rapidly during the last decade, and the processor manufacturers have developed a lot of techniques. Unfortunately, the factor of these techniques accompanies limitations, consuming excessive amount of power and serious thermal problem. These limitations are crucial for mobile devices. In this paper, we present a core allocation scheme for AMP based mobile devices. By using a lightweight scheme to classify workloads based on CPU utilization, the scheme assigns them onto the corresponding cores of AMP. Our scheme can mitigate the power consumption without performance degradation or with better performance for parallel applications.