CCAST, World Lab, Beijing 100080, Peoples R China
; CAS, Inst High Energy Phys, Beijing 100039, Peoples R China
; NanJing Normal Univ, Dept Phys, JiangSu 210097, Peoples R China
In this work, we calculate the rare decays B-0 --> D-s(*-) K+ and B+ --> D-s(*+)(K) over bar (0) in the perturbative QCD approach with Sudakov resummation. We give the branching ratio of 10(-5) for B-0, Ds*-K+, which will be tested soon in B factories. The decay B+ --> D-s(*+)(K) over bar (0) has a very small branching ratio at O(10(-8)), due to the suppression from CKM matrix elements \(VubVcd)-V-*\. It may be sensitive to new physics contributions.