Copper-silver bimetallic strips prepared by cold roll cladding have been treated by diffusion annealing in the temperature range 250-800℃. The interface bonding level and the hardness in the matrix copper and silver have been determined and the microstructure in the interface region has been observed. The interface bonding level is essentially improved under the conditions of annealing at both temperatures 400℃ and 800℃. A high diffusion temperature can make the hardness reduce in the strips. Recrystallization just starts in the strips annealed at 250℃ and mainly emerges at 400℃. Annealing above 600℃ can produce the fine grain areas between the interface and the silver matrix. If diffusion treatment induces the recovery, recrystallization or the partial fusion at the bonding interface, the interface bonding level can be enhanced.