With application of micro-nano pressing technology (MNPT) polyamide 6 (PA6) and 304 stainless steel were integrally molded, and the mechanical properties and structure on the interface of plastic and metal were investigated in the study. The micro structures on the stainless steel specimen surface were achieved by physical and/or chemical surface treatment techniques including polishing and etching methods, respectively. The tensile shear strength and work of fracture for the integrally molded specimen were influenced greatly by the surface treatment on stainless steel. The maximal tensile shear strength and the fracture work for the MNPT molded sample reached up to ca. 11 MPa and 17 KJ/m(2), respectively. In addition, the interface fractography of the MNPT molded specimen was characterized by scanning electron microscope (SEM) and atomic force microscope (AFM). These results indicated PA6 melt flew into the micro and/or nano holes on the chemical etched metal surface during hot press molding to form micro mechanical interlock structure to prepare strong MNPT molded samples.