Mortar is a construction material commonly used in building and road infrastructure. Some constructions that use mortar include Lane Concrete (LC), species, light brick adhesives, wall plaster, mechanical installation, and others. The purpose of this study was to analyze how the effect of mixing HDPE plastic waste fibers with variations of 0%, 2%, 4%, and 6% without any additives on compressive strength, workability, and mortar weight. This variation is used to replace cement, where the amount of fiber is calculated from the weight of the cement. This research is expected to reduce the amount of plastic waste in Indonesia. This study was carried out at the age of 7 days and 28 days using cube specimens with dimensions of 15 cm × 15 cm × 15 cm. The specimens amounted to 24 which will be tested with compressive strength by curing first. Based on the results of the test, the highest compressive strength for fiber mortar at 2% fiber variation at 28 days is 14.47 MPa, this result shows an increase in compressive strength of normal mortar or 0% fiber. The results of the mortar at the age of 7 and 28 consecutive days increased, where the compressive strength at 7 days was 12.56 MPa and for 28 days it was 14.12 MPa for normal mortar or 0% mixture. Whereas the addition of compressive strength fibers decreases with the increasing number of fiber mixtures. For weight, fiber mortar has decreased heavily where normal mortar at 28 days has a weight of 7696 grams, while the weight of mortar is 2%, 4%, 6%, age 28 days are 7640, 7422 and 7280 grams, respectively