The Deoxys-BC adopting the SPN structure and TWEAK framework is a lightweight tweakable block cipher published at ASIACRPYPT 2014.By researching the internal characteristic and key schedule of the Deoxys-BC,a 6-round meet-in-the-mid-dle distinguisher against the Deoxys-BC-256 and a 7-round meet-in-the-middle distinguisher against the Deoxys-BC-384 are con-structed with controlling tweak differential,differential enumeration and tweakey differential superimposing elimination tech-niques.A meet-in-the-middle attack against the 9-round Deoxys-BC-256 and the 11-round Deoxys-BC-384 are improved by using the distinguisher.The attacks can reduce the number of guessed bytes and achieve a reduction in the complexity.Compared with the existing meet-in-the-middle attack results of Deoxys-BC,its time complexity and storage complexity are significantly reduced