Abstarct: Due to the increasing production of plastic materials, there is an international concern about disposal or recycling of plastic waste in the world. One of the ways to reuse plastic waste is to use it in the engineering works to modify mechanical properties of loose soils. The purpose of this research is to find a way to reuse a particular kind of plastics (bottles of dough, soft drinks, mineral water, etc.) in geotechnical works to improve soil. In this paper, the mechanical behavior of Anzali Port sand, reinforced with 1×1 cm polyethylene terephthalate chips and 1×5cm strips, 0.1 , 0.5 , 1 and 2% and polyethylene terephthalate fibers to 0.1 and 0.5% of the dry weight of the soil which were arranged separately, was evaluated. Samples were prepared at the relative density of 75%. The effects of parameters such as dimensions, the weight percentage of reinforcers on mechanical behavior of the soil were investigated. The results of the experiments showed that although the polyethylene terephthalate chips and strips improve the mechanical behavior of sandy soil, but the effect of fiber reinforcers on soil mechanical properties has been much higher. Also, the optimum percentage of polyethylene terephthalate chips and strips reinforcers was 1% of sand dry weight and the optimum percentage of polyethylene terephthalate fibres was 0.5% of sand dry weight. The comparison between reinforced and unreinforced samples showed that reinforced specimens had more ductility and resistance. Also the maximum increasing in bearing capacity for samples reinforced with the optimum percentsge of chips, strips and fibers was 75, 92 and 191%.