The dependences of stress on strain, strain on the critical current density, and the relation of Jc(H) at several strains were measured in Bi-2223 silver clamped thick film. The results indicate that the stress-strain curve exists two strain transitions which are respectively correspond to the beginning and ending of breaking in Bi1.8Pb0.4Sr2Ca2Cu3Oy thick film. At △X/X≤2.5 % , the critical crrrent density Jc decreases slowly with △X/X increasing. At △X/X≥2.5 % , Jc decreases rapidly with △X/X increasing. As strain increases,the characteristics of Jc(H) decrease rapidly and the weak link junctions emerges obviously. The mi-crostructures show that the decrease of Jc and the variance of characteristics of Jc (H) relate to the breaking of intergrains and grains in the thick film.