This report deals with the cause of characteristics deffects of carbon composition film resistors.It is supposed that the main electrical properties of these resistors will be improved by adding the plasticizer of resin to the composition of films to raise the elasticity of films and the uniform distribution of carbon black in films.The report also gives a brief account of the functional mechanism of dibutyl phth-alate as a plasticizer in composition films and describes in detail the effects of the plasticizer on the temperature coefficients

voltage coefficients and noise levels of composition film resistors.The conclusion points out that 10% of dibutyl phthalate added to the composition of films will improve to a certain degree the above electrical properties with no adverse effects on the thermal stability.