Different construction orientations have a significant influence on the mechanical properties of the standard samples of fused deposition modeling (FDM). In this paper, polylactic acid (PLA) wire rod was used to prepare three kinds of printing samples in three different directions: standing, side standing and lying down, The digital image correlation (DIC) method was used to analyze and record the tensile and bending deformation process of the sample in real time. The real deformation and strain of the sample can be obtained effectively by using the measurement system, and the more accurate stress-strain curve can be obtained combined with the test machine data. Through the observation of the linear region in strain nephogram, it can accurately predict the time and location of fracture, and compare the mechanical properties of different oriented forming processes on printed products performance impact. The test results show that there is no obvious necking phenomenon in the tensile test and three-point bending test, and its deformation, elongation and strength are also the lowest, showing the characteristics of brittle materials. The lateral vertical has good tensile properties. After the necking phenomenon occurs, it will fracture after a small deformation, and the force that it can bear presents a linear downward trend until it breaks. The strength of the lying down type are similar to those of the side standing type, and the necking phenomenon occurs until the fracture deformation is larger than that of the side standing type, and the stress decreases gently with the increase of deformation, showing the best mechanical properties in strength and ductility.