Friction Stir Welding is a connection by utilizing heat that occurs due to friction of the pin tool to the workpiece, this type of connection was first discovered by Wayne Thomas at The Welding Institute (TWI) in 1991. Friction Stir Welding has several parameters that can affect the results of welding such as, parameters of rotational speed, feed rate, depth of plunge, temperature, and variations in the form of pin tool. The purpose of this study was to determine the strength of the feed rate parameters during the welding process with High Density Polyethelene (HDPE) material by testing tensile, bending, and macro structures in FSW welding. For this study using the parameters of the influence of the feed rate on the mechanical strength of welding friction stir welding in high density polyethylene (HDPE), variations in feed rate used in this study are feed rates of 10mm/min, 14mm/min, and 20mm/min with rotational speeds of 900 rpm, tests conducted in this study are tensile testing with ASTM D 638 standard, bending testing with ASTM D 790 standard, and macro structure testing. From the results obtained in this study indicate that the tensile test results that have the highest value are in the feed rate parameter of 14mm/min with a value of 16.2 MPa while the lowest results are at a feed rate of 10mm/min with 13.6 MPa, and for bending testing produces the highest value found in the feed rate parameter of 14mm/minute with a value of 16.2 MPa while the lowest value results found at a feed rate of 10mm/minute with a value of 15.8 MPa. For testing the macro structure there are many defects that occur at 10mm/minute variations in feed rates.