In this paper, we propose a cost-effective reconfigurable accelerator for the platform-based system-on-a-chip (SoC) design. Based on the proposed design methodology, the reconfigurable computation array (RCA) can be landed with the features of high usage rate and low hardware cost without sacrificing multimedia computation performance. The RCA consisting of 8 type 1 grouped processing elements (GPE1’s), 3 GPE2’s and 1 GPE3 is capable of configuring two 16x16-bit multiplication, eight 8x8 multiplication, and sixteen 8-bit absolute operations in different connection topologies. Via the cost-effective RCA, the number of GPEs can be saved up to 25% and the usage rates of the RCA compared with that of [8] for motion estimation (ME), RGB2YUV and DCT/IDCT can be improved by 25%, 18.7%, and 23.9%, respectively.