The growth of ultrathin films of 2,5-bis(4-1,1':4',1"-terphenyl)-thiophene (3PT) and weak epitaxy growth (WEG) behavior of phthalocyanines (H2Pc and ZnPc) on 3PT ultrathin films were investigated by atomic force microscopy, X-ray diffraction (XRD), and select area electron diffraction (SAED). Domain size of the monolayer films can reach 10 mu m at the substrate temperature of 190 degrees C. The second layer films begin to show Volmer-Weber growth mode. This growth mode transformed without a concomitant phase transition. The XRD and SAED measurements indicate the monolayer and double-layer films of 3PT have identical in-plane and out-of-plane structure. The epitaxial ZnPc films have a similar orientation or intertexture shape utilizing 3PT monolayer and double-layer films as the inducing layer. By comparison with utilizing para-sexiphenyl (p-6P) as the inducing layer, the morphology with clear borderline of epitaxial films with different orientations on joint of neighboring 3PT monolayer domains disclosed that the 3PT monolayer films have characteristics of crystal. Meanwhile the distinguishing effects of inducing layer phase state on morphology of epitaxial films were shown, respectively.