Additive manufacturing technologies continue to develop extremely fast. Their opportunity of reproducing any given complex geometric form they superior to traditional production technologies. Despite the rapid development and distribution, there are still areas that require special attention for the study of the behavior of materials for 3D printing. This work presents method of defining mechanical property of PLA plastic for 3D printed parts. For this, a full-scale experiment was carried out using specimens created by 3D printing. After carrying out the tensile test, the tensile diagram was determined.