Reversible data hiding has been a hot research topic since both the host media and hidden data can be recovered without distortion. In the past several years, more and more attention has been paid to reversible data hiding schemes for images in compressed formats such as JPEG, JPEG2000, Vector Quantization (VQ) and Block Truncation Coding (BTC). Traditional data hiding schemes in the BTC domain modify the BTC encoding stage or BTC-compressed data according to the secret bits, and they have no ability to reduce the bit rate but may reduce the image quality. This paper presents a novel reversible data hiding scheme for BTC-compressed images by further losslessly encoding the BTC-compressed data according to the secret bits. First, the original BTC technique is performed on the original image to obtain the BTC-compressed data which can be represented by a high mean table, a low mean table and a bitplane sequence. Then, the proposed reversible data hiding scheme is performed on both the high mean table and low mean table. Our hiding scheme is a lossless joint hiding and compression method based on 2×2 blocks in mean tables, thus it can not only hide data in mean tables but also reduce the bit rate. Experiments show that our scheme outperforms three existing BTC-based data hiding works, in terms of the bit rate, capacity and efficiency.