In this paper, a low-complexity 8?8/4?4 Adaptive Block-size Transform (ABT) scheme is tentatively proposed for the Chinese Audio and Video coding Standard (AVS)1. In the proposed ABT scheme, an integer 8?8 transform is derived from the integer 4?4 transform used in AVS according to a transform extension principle. The 8?8 transform not only has high energy compacted property but also can be merely implemented within several additions and shifts, and all intermediate results are limited with 16-bit. The 8?8 transform and 4?4 transform can be merged together and share the same scale matrix so that the hardware units and storage resources are efficiently saved for both encoder and decoder. The experimental results on numerous sequences show that the proposed ABT scheme can achieves significant performance improvement for AVS.