The melting and crystallization behaviors of TPU/PA612 blends were investigated with DSC. The results show that strong interaction was existed between PA612 and TPU chains. As the content of TPU increased, the crystallinity of PA612 decreases by degrees .The interactions affect each other’s crystallization. At high assay of PA612, TPU can not crystal. The interaction was especially notable in melting state due to the diffusion of the chain segment.